Page  99

CHAP XIII. Of the Oeconomy of Sensation, as far (at least) as it concerns our present Purpose.

WHEN I had written this Tract thus far, I judged it best, first, to publish that of Animal Mechanism, because it contained those Principles that would explain the Matter of Opium; therefore laying this aside, I applied my self to that: But a New Art, rightly to Spell, Write, and Sweeten all Languages, (that I since call'd Phono∣graphy) coming into my Mind, and thinking it might be very useful, and likely to lie for ever in Darkness, (as it had always been) unless I under∣took the Drudgery, I set my self to it; which ta∣king up more Time than I imagined, has to this day hindred the finishing of that Tract of Animal Mechanism, which I now much want, (as was in∣timated:) Therefore because I resolv'd to publish this, (that was so long since promised) I am now forced, for want of that Book, to premise here some Things, concerning the Oeconomy of Sensa∣tion, and the Nature of sensitive Pleasure, in order to explicate the Effects of Opium, which might have been spared, if that of Animal Mechanism had been published.

Considering that Opium must (as was shewn) operate by pleasing the Sense of Feeling, it will be requisite to consider,

• 1. The Oeconomy of Sensation, as far as it concerns the present Purpose, for which this Chapter is de∣sign'd.
• Page  1002. The Nature of sensitive Pleasure, and its Effects upon the sensitive Soul and Body, which is to be the Subject of the following Chapter.

Five Things mainly concern the Oeconomy of Sensation: 1. The Object. 2. The external Me∣dium. 3. The Organs of Sensation. 4. The Ani∣mal Spirits, (or internal Medium.) 5. The sensitive Soul.

• 1. The Object is the Thing perceiv'd by any of the Senses; as, Light by the Eye; Sound (or tremulous Motion of the Air) by the Ear; Odour by the Nose; Tastes by the Tongue; Opium by the Feel∣ing, or (as Helmont calls it) the Gustus (or Taste) at Stomach.
• 2. The External Medium of Sensation is that which receives Impressions from the Object, and conveys them to the Organs of Sensation. Thus the Air conveys Sound (or tremulous Motion) to the Ear, Light to the Eye, and Odour to the Nose.
• 3. The Organs are the Parts of the Body that God has fram'd to receive those Impressions, and communi∣cate them to the Animal Spirits, (or Internal Me∣dium.) Thus the Eye is the Organ to receive the Impression of Light, the Ear that of Sound, &c. And the Membranes in all Parts of the Body are the Organs that receive Impressions from Objects in the case of Feeling, which is our main Con∣cern.
• 4. The Internal Medium is the Animal Spirits that receive the Impressions from the Organs, and con∣vey them to the Sensitive Soul.
• 5. The Sensitive Soul, which perceives those Im∣pressions convey'd to him by the Animal Spirits; which Perception is Sensation.

Page  101I. The Part, Office, or Business, of the Object, in the Matter of Sensation, is to make a sufficient Impres∣sion either upon the External Medium, (or Air) as in the case of Hearing, &c. or immediately upon the Organ, (or Membrane) as in Feeling, &c. There∣fore if there be no Impression of Light, Sound, (or tremulous Motion) Odours, Relishing Particles, &c. there can be no Perception; or if the Inpressions thereof be weak and faint, the Perception, or Sen∣sation, must be accordingly; or if it be so incon∣siderable, that it cannot at all affect the sensi∣tive Soul, then is there no Perception thereof. For,

1. Sensitive Perception is not infinite, because there are Degrees of Light, Sound, &c. that cannot be perceiv'd, tho' they must be very small, and in∣considerable: Thus the Light of a Candle at so great a distance that it can hardly be perceived, is some Degree of Light, and makes its Reflection proportionably from a Wall, Tree, &c. yet cannot that reflected Light from the Wall, or Tree, be perceived; so the smallest Things cannot be per∣ceived. Yet GOD has in His Wisdom and Good∣ness so ordered it, that,

2. Sensitive Perception is of excessively small Things: Thus the Sound of a Pin's Head, falling into a Brass Caldron, is heard at some distance; the hundreth part of a Grain of very hot and biting Things, are sensibly tasted; the thousandth part of a Grain of Ambergrise, Musk, &c. very sensibly smelt; the Light of an exceeding small Spark, struck out between Steel and Flint, is perceived at a great distance: And Light in general consists of such tenuio•s Particles, (if material) that none ever could take any estimate of their Bulk. So the Feeling at Stomach takes very eminent and remark∣able Page  102 notice of (as was said) the Vomitery Particles of Crocus Metallorum, or Regulus of Antimony, which are so small, that a thousand Vomits thereof does not sensibly diminish the Crocus, or Regulus, either in weight or bulk. Therefore it is no Wonder if a Grain of Opium should affect the Feeling so sen∣sibly as it does, especially at Stomach, tho' it can∣not make any considerable Alteration of the Bloud.

3. That whatever affects, or makes impression, up∣on the Organs of Sensation, is in the same moment perceived by the sensitive Soul▪ So that it is no Won∣der, that a Grain of Opium operates in so short a time, that is, as soon as a Tincture thereof insi∣nuates it self through the Crusta Carnosa to the sensile Coat of the Stomach; whereas it must take a very long time, if it operated as an Alterative of the Bloud.

Now Note, 1. That there is no way for any thing to operate upon the sensitive Soul, in so small a Quanty, as Opium operates, or in so short a Time, as by affecting the most exquisitely dis∣posed Membrane at Stomach. 2. That the speedy Way that God has contrived for our Refreshment, Comfort, raising of our depressed Spirits upon any sudden Occasion, as in Delīquiums, Faintings, Syn∣copes, Leipothymies, &c. is by the Senses; especi∣ally that most exquisite Sensation at Stomach, be∣cause Refreshment by Nourishment and Alteration, cannot be perform'd but in a long time, where∣in we might in many Cases perish before we could be relieved thereby: Thus a pleasing, and there∣fore comfortable Odour, excites the Spirits in a moment; the sight of a beloved Mistress, or dear Friend, raises us immediately, when we are most cast down; as does also sweet Melody, and an aggreeable or pleasant Sensation at Stomach, as Page  103 of Wine, Cordials, hot Spirits, &c. I hope none will say, That Musick, the sight of a Bag of Mo∣ney, &c. send Eff•uvia's for that end, yet are great Comforters.

II. The Part, Office, or Business, of the External Medium, in the Oeconomy of 〈◊〉, being to re∣ceive and convey Impr•ssions, as Sound (or tremulous M•tion) from a Bell to the Ear, &c. it must be duly qualified for that purpose.

It is true, that we are not concerned as to this external Medium (or Air) in our Case, because Opium affects only our Feeling internally, and im∣mediately at Stomach, where it touches the very Organ, (or M•mbrane:) However, because this External Medium (or Air) is to receive and con∣vey 〈◊〉 after the same manner, from the O•ject to the Organ, as the Internal Medium (or Animal Spirits) is to receive them from the Or∣gans, and convey them to the 〈◊〉 Soul, and therefore bear exact Analogy to each other; and because the External Medium (or Air) is more obvious than the Internal, (or Animal Spirits) I think it very convenient to consider its Disp•si∣tions and Requisi•es, as a Medium, that we may the more clearly perceive those of the Animal Spi∣rits, as such.

1. It is requisi•e that the Air, as a Medium, (be∣ing a fluid Body) should be springy, (or elastick) be∣cause nothing but what is so is capable of trem•lous M•tion, (which is material Sound) nor of Compres∣sion, without which, a loose, 〈◊〉, yielding Fluid, as the Air is, cannot be fit to convey Im∣pressions; for the more solid any thing is, the fit∣ter it is for that end; therefore Compression must render it firm, tight, and close, that one Part may briskly communicate its Motion, or Impression, to Page  104 the next to it, and that to the next to it, and so •ndefinitely; yet can it never arrive at the Per∣fec•ion of a Solid in carrying of Impulses: Henco it is that Sound decays by degrees. However, it has many great Advantages over a Solid, as a Medium for the purpose of Sensation:

• First, Because it receives Impressions better.
• Secondly, Because a Solid having weight, could not be so easily moved, in order to convey the 〈◊〉.
• Thirdly, Because there would be no living or being in a Solid, as there is in the Air.
• Fourthly, Because if moved, &c. it would deal very rudely, grate and tear the very Organs, and not gently touch them, as the yielding Air does; besides many other Inconveniencies, which to mention is to little or no purpose. So being fluid, tenuious, yielding, &c.

•. It is (as was intimated) requisite, that it should be compressed, for the better conveyance of Impres∣sions, the more the better; for then (like a Gut blown very tightly) a small Impression cannot be made upon one part thereof, but it is communi∣cated a good way to other Parts: But if not com∣pressed, you may compare it to a Gut half full of Air, or a loose soft Lock of Wooll, that yields, and will not convey Impressions at all, or very faintly; whereas if the Air be tightly compressed in a Gut, &c. you cannot make a little Impression (or Dent thereby) at one end of it, but the whole contain'd Air, having less room by so much, becomes more compressed, and consequently thrusts so much the harder against all the sides, and the fa•ther end there∣of, especially if the Gut has no vent, or that it be not too wide; for, in the first Case, the Air, that should be kept in for the communication of the Impression, Page  105 having Liberty at the Vent, takes its course that way, and so disappoints the continuation of the Impulse, (or Impression) either wholly, or in great measure; •n he Second Case, the Impulse bearing but a small Proportion to the whole, and also de∣caying in Proportion to the Liberty it has to widen, becomes much more insensible, or less remark∣able.

Thus if you make a Dent, or Impression, of the bigness of half a small Pea, at one end of a Gut so filled with Air, that is of the bigness of one's Thigh, and two Yards long, it will bear a very small Proportion to the whole, and consequently very insensibly affect it; for 'tis like a Drop (as the Saying is) added to an Ocean; but if an Im∣pression (or Dent) of that bigness be made upon a Gut no bigger than a Pea in diameter, the Thrust, or Impression, will be very considerable at the other end, for the Reasons aforesaid. So that you plain∣ly see, 1. That the more Air is compressed, the better it conveys Impressions: Hence it is that we hear Sounds better, and farther, when the Air is most compressed, and the Quicksilver high in the Barometer, (or Weather-glass) and upon low Grounds, tho▪ flat, and without any hollowness, than on the tops of high Hills that are flat also; because the Pressure of the Air is less on high Hills. I mention the Flatness in both Cases, le•t any should attribute it wholly to the more free Ex∣pansion of the tremulous Motion on the tops of Hills, which indeed is a Reason where the Flatness is not alike, as far as the Sound goes. 2. That the nar∣rower the Gut, Duct, or Pipe, the Air is in, the smarter and more sensible will be the Impression at the farther end thereof, which may be confirmed and illustrated by many Demonstrations, Instances, and Experiments.

Page  106Hence it is, That if one speaks at one end of a Pipe, that is but an Inch in diameter, you'll hear it much better at the other end than in a close Gallery of the same length, tho' this will advan∣tage it much more than the open Air: That if one speaks ever so slowly at one end of a long Piece of Timber, it is manifestly and distinctly heard at the other end, through the narrow Vessels, and be∣tween the Fibres of the Wood: That all Sounds are sharper in narrow Pipes, &c. How easie is it then to contrive invisible Whispering-Places, which the World so much admire, and some Religions make such great Use of to deceive the People by preten∣ded Divine and Oracular Responses, of which the Reader may hereafter be aware.

It is for like Reasons that Guns, Bells, &c. are better and farther heard along hollow Valleys, than upon Plains; that Sounds are heard so well the ways that Rivers run; for it is a vulgar Error that the Water does advantage the Sound upon Rivers; if it did, you'd hear farther at Sea than upon Land; which is so false, that the quite contrary is true, Sounds being much farther heard by Land than at Sea. It is a common Observation in Sea-Fights, that the S•und is heard at a much greater distance upon the Land than at Sea.

There is indeed another Advantage in Valleys, (and therefore upon Rivers) viz. the several Re∣verberations, or Eccho's, from the Hills and high Banks, Rocks, &c. on the sides thereof; but this not much concerning our Purpose, I must (for the present) pass them and several Observations upon Sounds.

For the aforesaid, and other ends, it is notorious that the Air is springy, and always under the com∣pression of the Atmosphere, or else it would be of little use as a Medium.

Page  107I know but one thing more to our Purpose that is worth the mentioning, in reference to the Ana∣logy between the Air and Animal Spirits, as Me∣diums of Sensation, viz.

3. It is requisite, or convenient at least, that the Air have an homogeneous Continuity, which much more advances it in conveying Impulses, (or Impressions) than when it is discontinued, divided, or sever'd, by other heterogeneous Particles, especially if these be in motion between the Parts of the Air; for then they very much disappoint and disgregate the Impressions made thereon.

Therefore it is, that we hear so much better after Sun-set, or in the Nights, especially the Summer∣time, than in the Day, when the Particles of Heat, and others thereby raised, do too much divide, discontinue, and disgregate the Impressions, and the Parts of the Air▪ Where you may observe how Good and Wise Providence orders Hearing to be more useful in the Night, when Seeing fails. It is a vulgar Errour, (tho' little thought so to be) That the Cause of the Difference of hearing Sounds before and after Sun-set, is the Noise that is made in the Day-time, and the Silence of the Evenings and Nights; which one single Instance (tho' thousands may be given) will fully demonstrate, viz.

In the Famous and Well-governed University and City of Oxford, there is scarce any Noise made at the Times of Divine Service on the Lord's Day, all People being either silent at Church, or shut up quietly and silently in their respective Houses or Colleges, (the Heat of the Days in Summer∣time, but mostly the good Order of the Place, causing it:) But after Sun-set, most People are out, walking and discoursing, or talking at their Doors, Arbours, or Gardens; and all Chil∣dren Page  108 (that noisie Part of Mankind) are now per∣mitted to go out, who act their Parts in Playing, Running, Calling, Yawling, and Crying out one to another; insomuch that (all things consider'd) I cannot imagine but there must be in general an hundred times more Noise made then, than in the the time of Divine Service in the Heat of the Day; yet may you, notwithstanding all the Noise, hea•, in the Twilight, any thing twice as far as in the time of Divine Service in the Heat of the Day, (I believe I might have said four or six times as far.) The same may be observ'd in any Town or City that is kept in good Order at the time of Divine Service, or in Camps, &c. upon several Oc∣casions.

It is not only consonant to Reason that the Air should be so discontinued by the Particles of Heat, &c. but obvious to the Sight that it is so; for in a great Heat, the Summer-time, and clearest Day, you may see the very Air in a wavering tremulous Motion, which could not be seen of it self, without the mixture of other Parts; for disgregation of Parts, (as you see even in pel∣lucid homogeneous Things powder'd) causes Opacity.

III. The Business, or Office, of the Organs of Sen∣sation, in the Oeconomy thereof, being to receive and communicate the Impressions to the Animal Spirits with all the smartness they can, it is manifest, that in the Membranes, (or Organs) Tension is their main Requi∣site. Hence it is that when the Tympan of the Ear is tense, the Cornea, and other Tunicles of the Eye sufficiently so, we hear and see acutely and accurately; to that end God has given us a Power to render the Tympan more tense when we listen; to contract the Pupilla of the Eye when we look very intently, &c. And we see, that when the Page  109 Cornea is relaxed, (as it is always when the Eye looks deadish, as in Sleep, Drunkenness, fainting Fits, &c.) yet then we either not seet at all, or much worse: So it is when the Tympan is relaxed. We also always put the Tongue in a tense condi∣tion, when we would taste a Thing exactly. So when any Part is relax'd by Warmth, &c. we do not feel so well and nicely, as when the Part is cold, or more tense, or rigid; nor in Sleep, as when awake, because all Parts are relaxed in Sleep, and contracted when we are awake, which ma∣nifestly appears,

• 1. Because we perspire less when we are awake, than when asleep, which happens because the Pores are closed by the Contraction, or▪ Constriction, when we are awake, and opened, or loosened, by Relaxation when asleep. In all Relaxations, as that which happens by Pleasure, Warmth, Leipo∣thymies, Sleep, &c. we perspire more; and less in Contradictions, by Cold, Fear, Grief, Pain, or any grievous Sensation, or Passion.
• 2. Because all Parts are firmer when we are awake, and more loose and flaccid when we are asleep; none can doubt but Firmness is from Ten∣sion, or Contraction: But in this matter you may expect farther Satisfaction by and by.

Obj. Some may needlesly say, How came Ten∣sion and Contraction to be Concomitants, or Effects one of the other, seeing we make Things more tense, as a Drum's Head, &c. by Extension, not Contraction?

Answ. I purposely started this Objection to clear the Case. Therefore, 1. Observe, That Violin-Strings will grow so tense (as will any thing else of like Nature) by Contraction in moist Weather, Page  110 that tears them to pieces sometimes upon that account, and always puts them upon a greater stress; for when a thing is fixed at both ends, it is the same thing to shorten, or contract, the String, to render it tense, as to take something from its length between those two fix'd Points; both the Contraction and the Winding do only take something of the Length away, that is between those two Points, where the Ends are fastned; which causes a great stress of the shortned String, to reach those two Points that it is fastned to: As, suppose you have a String of 11 Inches long, fast∣ned at both ends at the distance of 10 Inches, it will be very loose; then shorten it one Inch, by winding up so much, or by some means contract the String to 10 Inches, or any way shorten it an Inch; then it will just reach the Points, and be tense, if fastned at them. So there is Contraction necessarily causing Tension, which was to be de∣monstrated.

It will be the same in effect, if a String put round any thing is shortned by Moisture, or otherwise, it must grow more tense; and so must 500 Strings, if so shortned, or an entire Membrane that covers or includes the whole. Thus Membranes (as a Gut contracted upon included Air) must, when they contract, grow more tense upon the inclu∣ded Animal Spirits in the Nerves, or otherwise; for it is the same as forcing much Air into a nar∣row, or contracted Gut, or Bladder, which must make them tense, while the elastick Body must thrust out the harder, the more it is compressed. And that the Membranes, and all sensile Parts, are more contracted when we are awake, doth farther most plainly appear: Because,

Page  1113. The Cornea of the Eyes (which is a visible and certain sign of the Relaxation of all the sensile Parts of the Body) is relax'd in Sleep, as any one may see; for that is the cause of the deadness of the Eye in Sleep, which upon awaking is imme∣diately gone, by the Cornea contracting into a tense condition upon its Contents, by which means it becomes tense, rotund, hard, smooth, shining, and reflects a brisk Speck of Light, (as round Things do) which makes it look lively; whereas when 'tis lax, as in Sleep, Syncopes, Faintings, &c. it is uneven, soft, and reflects an uneven, dull, inde∣finite Light, all which causes the deadness of Looks. Therefore (as was intimated) there is no better sign of Relaxation than deadish Looks.

4. The Pupilla (which is another sign of Relaxa∣tion) is relaxed, or dilated, in Sleep, and contra∣cted when we are awake.

5. All Motions of the Body are better perform∣ed when we are awake; which argues the grea∣ter contraction of Parts; for Relaxation (as in Sleep, Deliquiums, Drunkenness, &c.) weakens all Motion.

6. That Efflorescence of the Skin which People have when asleep, (which is caused by the Re∣laxation of the Skin admitting the Bloud more into it; as Paleness is by the Contraction of the Skin in Cold, Fear, &c. repelling the Boud) dis∣appears upon awaking, by reason that the vigila∣tive Contraction (so I call it) does send the Bloud out of the Skin by squeezing it back, or repelling it.

7. Measure the Body ingeniously and accurate∣ly, and you'll find it contracted and narower, after awaking, than in Sleep.

8. Hence it is that you find, when the Body is pretty full of Moisture, and the Weather hot, a •udden Sweat upon awaking; because the whole Page  112 Body contracting, does, like the contortion of wet Linnen, cause an exudation of its Moisture, by a mechanical expression, or squeezing.

9. Hence also it is that we are subject to take Cold, even in a warm Room, if we watch long; because the Pores being closed by that vigitative Contraction, hinder Perspiration too long, and too much: Therefore it is that all Colds are worse to∣wards the Evenings, because that Contraction closes the Pores all day; and not only Colds, but many other Distempers, especially such as Perspiration is good for; as indeed it is for most Diseases, as be∣ing the most natural and considerable Evacuation: Most natural, because it requires no voluntary Mo∣tion, or Irritation of the sensile Parts, as that of Siege, Urine, &c. which either require the Will, or Irritation by Quantity or Quality, or both, or all three; but Perspiration (like Fumes in a Chimney) requires only that its little Funnels (the Pores) should be open, because our Fumes pass (as the other do) by their own natural Levity: And it is most con∣siderable, because universal, and that much more is evacuated that way, than by all Means and Ways whatsoever.

Hence it is that all Membranes gaining a Tension, by the vigilative Contraction in manner aforesaid, are more rightly disposed to receive and commu∣nicate smart Impressions to the Animal Spirits, while we are awake, which was the Thing aim'd at, and will be much more illustrated by the Consideration of the Animal Spirits, and the Sensitive Soul.

Note, That the Membranes, Vessels, and Roads of the Animal Spirits, being much narrowed and compressed by this vigilative Contraction, Two other main Requisites for exact Sensation do of Page  113 course follow, (so consentaneously do the Works of God conspire to their Ends) viz.

First, That an Impression made upon the Ani∣mal Spirits in Pipes so narrowed, is better, more exactly and smartly convey'd to the sensitive Soul, as has been shewn, by the Analogy of the External Medium in slender Pipes.

It is by such narrowing of the Nerves, Pipes, Roads, &c. of the Animal Spirits, that cold Wea∣ther, which contracts the Parts, makes our Feeling more nice and smart than warm Weather, which relaxes the Vessels, and gives the springy Animal Spirits (for such they are, as shall, by His Assi∣stance that made them, appear) leave to expand, by which means, and the Vessels widening, the Feeling grows duller, for want of compression of the Spirits.

By what has been said, you may see why Per∣sons of a fine and delicate Texture (that is, of smaller and slenderer Vessels) have a more exquisite Feeling; that little Animals, as Spiders, Flea's, and many such, have most nice and accurate Feeling, because their Nerves, Vessels, Pipes, &c. are pro∣portionably small, and the smaller they are, the more accute is their Feeling, for the Reasons afore∣said; which was absolutely necessary, because they deal with small Things proportionably, as their Food, Treading, &c. and that small Things may harm them, unless they take distinct notice there∣of to defend themselves; whereas Elephants, Ca∣mels, Horses, &c. can, because of their large Vessels, scarce feel such Impressions, as would crush those little Animals to pieces. Lord, how manifold are Thy Works! In Wisdom Thou hast made them all!

Page  114It is from this Fineness and delicate Smallness of the Nerves, Fibres, and Membranes, &c. that one Part has a more exquisite Sensation than another, and that the extream Parts have (generally speak∣ing) better Feeling.

Secondly, It follows, that by reason of the vigi∣lative Contraction of the sensile Parts, the Animal Spirits must gain a considerable compressure, whereby (as the External Medium is rendred fitter to con∣vey Impressions by the help of Compression) they are better disposed to convey Impressions to the sensi∣tive Soul; for the Internal and External Medium ha∣ving like Office in the Oeconomy of Sensation, and (as you'll find) like Qualifications, must be affect∣ed alike by Compression; but whether they are the same thing, or no, I shall not need the Discussion of that Point here; therefore I leave it to my Tract of Animal Mechanism.

IV. The Office, or Busin•ss of the Animal Spirits (or Internal Medium) being to receive Impressions from the Organs, and convey them to the sensitive Soul, as that of the External Medium (or Air) was to re∣ceive them from the Object, and convey them to the Organ; the requisite Dispesitions for its purpose, are manifest from the Analogy of the External Me∣dium, viz.

First, That they should be springy, (or elastick;) and that they are so, appears,

• 1. From their very Office, which being tenuicus and fluid, they could never perform (as the Air cannot) without being springy.
• 2. If they were not elastick, and thereby com∣pressible, their Vessels could never be so contracted (as has been shewn) without squeezing them quite Page  115 out of them, which is a Disorder not to be sup∣posed in the Works of God.
• 3. If they were not elastick (or springy) they would not fill their Vessels upon Relaxation thereof, which would leave a Vacuity, and thereby cause a discontinuance of Motion, or (at least) a great disorder of it▪ which would cause dismal Convul∣sions, if not Death it self; which is most likely.
• 4. They could not be so active, nor indeed at all active, without springiness; for they cannot act up and down, and all manner of ways, (as they do) by either Levity or Gravity, or by any other known or imaginable Qualification, but Elasticity (or Springiness)
• 5. It cannot be conceived why they should be more active one time than another without Elasti∣city; but they are more active at one time than another, as appears by several Places or Passages of the Premises, and in the waking more than in such as are asleep.
• 6. It is manifest, that they are elastick, by their springing into a Limb held up or down; and, that with such Force as to cause a great Pain, after they have been excluded from it by some Acci∣dent, as leaning, or pressing too hard upon a Nerve, &c. for neither Levity nor Gravity can do so, especially both up and down (as was said;) nor is there any Propulsory Engine for them, as is for the Blond, therefore it must be from their springiness.
• 7. They could not cause brisk and smart tre∣mulous motions in the Body, if they were not ela∣stick, for such cannot be conceived by any means without it▪ but there are several brisk and smart tremulous motions, caused by the Animal Spirits, as in the Shiverings of Ague Fits, Frights, Cold, Sur∣prizes, sudden or exquisite Pain, Tremors of the Hands, Head, &c. in Old Age, in some Conv•,Page  116&c. Therefore the Animal Spirits that cause them are elastick.

• 8. Muscles have no springiness of themselves, when the Animal Spirits are excluded from them▪ as in Palsies, &c. but all Muscles in their Exertion are very springy, insomuch that if you hold any of them back, or restrain them from their mo∣tion, and again suddenly leave them at liberty during the Exertion, they, or any Part moved by them, will spring out very violently, as in Flip∣ping, an Arm held back, &c.

  But nothing proves this Matter better than the Tongue, in forming the Sound of the Letter R, for in that Case the Tongue, after it is put in Ten∣sion and Exertion, being suddenly hit against the Inside, or Gums of the Upper Teeth, does there∣upon (as Springy Bodies used to do) fall into a tremulous motion, or jarring, that causes the snar∣ling sound of R, which nothing but springy Mat∣ter can do.

• 9. Were they not springy, they could never convey the tremulous motion of sound to the sensi∣tive Soul, and indeed over all the Systeme of the Nerves, by which is caused (as may be proved) that Motion of Consent call'd Dancing, and the Fingers, &c. to move and keep Time with the Musick, even when it, or the Finger, are not as much as thought of, because the Animal Spirits have the same Capacity with the Air, to receive and convey it, by Reason of their springiness, and greater by Reason of their more forcible Com∣pression by the Vigilative Contraction, super added to the Compression of the Air, under which they are, as well as the Air it self, as plain Reason tells us; for that which Compresses the whole Body, must needs Compress the Animal Spirits: The Page  117Experiments of the Air-Pump do confirm the same.
• 10. There can be no doubt but the Animal Spirits are nourish'd, or sustain'd by the Air, if they be not Air; therefore they are elastick. What needs any more Arguments, when several of the former are Demonstrative? And, that,
• 11. All Physicians and Phylosophers (that I know of) do allow, that the Animal Spirits are ela∣stick.

Secondly, It is requisite, (as was said of the Ex∣ternal Medium) that they should be compressed, to render them fit to convey Impressions; and that they are compressed is evident (as was before in∣timated.)

1. By the Atmosphere. 2. By the Vigilative Contraction; which makes them much more dis∣posed to convey Impressions than the External Me∣dium; besides, that very often Two other Contra∣dictions (that are shewn in the remaining Part of this Chapter) are added thereto; and, that the Animal Spirits are wholly contained in Pipes, (to prevent their Expansion) and that of the nar∣rowest sizes that can well be imagined; but the Air, or External Medium, is at large in the At∣mosphere; so that all the Impressions made upon the Animal Spirits are very tightly, closely, and smart∣ly convey'd, nor have they but a little Way to pass, that is, the length of the Animal at most, which also may be some Advantage to small Crea∣tures. But in Sleep the Vigilative Contraction being lost, and the Animal Spirits thereupon expanded, all Impulses must needs be carried very faintly, both because the Organs (or Membranes) are in∣disposed by Relaxation, and the Animal Spirits by Expansion upon that Relaxation, for want of due Compression to fit them.

Page  118Thus have you (after many vain Enquiries) the true Mechanical Cause of the Difference of Sensation, Sleeping, and Waking, and the plain Reason, why our Motions are so feeble in Sleep, viz. Because the Animal Spirits have lost much of their Force, Sprin∣giness, &c. for want of due Compression, by Reason of the Relaxation of all the Vessels that include the Spirits.

Thirdly, It is (in some Measure) requisite, that the Animal Spirits should have an Homogeneous Con∣tinuity, as was shewn by the Analogy of the Ex∣ternal Medium, which does not convey Impressions as well in the Heat of the Day, as in the Night, or after Sunset; because its Parts are more discon∣tinued and disgregated by the Particles of Heat, Fumes, &c. in the Day Time; nay, if Things be discontinued, they never carry Impressions so well, tho' placed contiguously afterward; Thus a long Tree that conveys sounds so exactly from one end to the other, while all is continued, and in one Piece, will not convey the sound so well if it be cut into many Pieces, tho' they are afterward put close one to the other.

As to this Matter of Continuity in the Animal Spirits, seeing it does not much concern us, and that People in a State of Health are supposed to have it, and that it is not our Business here to en∣ter upon the Consideration of Nervous Distem∣pers, I need not use any more Words about it; but that if it any Way happens to be discontinued, as either by the Penury thereof, that they do not quite fill all Parts of their Vessels, or any Matter intercepting their Parts, or that the Vessels should be so relaxed, or widen'd, that the Animal Spirits cannot so well fill them up, &c. such Causes must Page  119 destroy or lessen Sensation, tho' the bare mixing of Fumes with them would not (considering the shortness of the Way that Impressions are carried in Animals) much alter the Case, as you find Fumes in the Air do not much hinder sound at the distance of a Yard or Two, wherein it is insensible (to common Observers at least;) so that if some Fumes from a Grain or Two of Opium, did mingle with the Animal Spirits, it would not cause a sensible difference of Feeling in the short space of the length of an Animal: But I have proved, That no such Fume from the Opium mixes with them, therefore need say no more of this Matter.

V. The Office or Business of the sensitive Soul in the Oeconomy of Sensation, being to perceive the Impres∣sions conveyed to him by the Animal Spirits, that he may, if he finds them disagreeable, bestir himself in Defence of the Animal.

First, It is requisite he should attend to all Impres∣sions offer'd him by the Animal Spirits, otherwise Impressions of great Concernment may escape his notice, and consequently want his Assistance by Way of Defence. For

It is manifest, That when his Attention is di∣verted by any Object, more especially by such as mightily pleases him, as in the Act of Venery, and other Pleasures, especially if intense, that he does not perceive other Objects at the Time that he is so diverted; and if the pleasant Diversion be in∣tense, and permanent, as in the Case of Opium and Wine drank in a considerable Quantity, he is so taken up, diverted, or charm'd therewith, that he does not attend to the Business of Sensation. This is one Reason why such as are far gone in Page  120 Drink, have none of their Senses aright; but as to the Illustration of this Matter you may expect more hereafter.

Note, That the sensitive Soul is the only Thing i• an Animal that has Perception, and therefore the only Thing that is sensible of any Grievance, Weariness, Hunger, Pleasure, Comfort, &c.

Secondly, It is requisite, that it should use all Means that is in its Power, that the Impressions should be brought to it very entirely, exactly, smartly, &c. so as to have due notice of all Objects, and the smallest Impressions that may be.

For which good Ends and Purposes God has en∣dued the sensitive Soul (as will be fully proved) with a Power of contracting all the sensile, small, and slender Pipes, Vessels, or Passages of the Animal Spirits, for the more express, distinct, and accurate Conveyance of all Impressions by the Help of Compression; Therefore the sensitive Soul taking the Advantage thereof, for better In∣formation, in order to Self-Preservation, does (by the Appointment of the Preserver of all Things) execute his Power by the aforementioned Vigila∣tive Contraction of those Parts, to cause their Ten∣sion and greater Compression of the Animal Spirits, to improve the Impressions that are to be convey'd to him, and render them more observable; This God, who has made nothing to be idle, and par∣ticularly ordered the sensitive Soul in Adam for Labour, especeally in Reference to their own Safety and Preservation, has made to be the ordinary Employ or Day-Work of the sensitive Soul, that by the said Vigilative Contraction, the Organs, Membranes, Vessels, &c. may be render'd more tense and firm, and the Animal Spirits more compressed, Page  121 springy, prompt, flippant, and forcible, for the Benefit of Sense and Motion, upon all Occasions of Defence, Flights, Struggles, &c. which is our State of Vigilancy (as has been intimated.)

But the keeping of the said Parts, Membranes, &c. in continual Contraction, even against the Renitency of the elastick Spirits, (which resist, and thrust the harder against their Vessels, by how much the more they Compress them by the Vigilative Contraction) being a continual tedious Labour and Fatigue, of which the sensitive Soul being sensible, (as the only Perceiver of Lassitude, or indeed of any Thing besides, in an Animal) and in his Nature but material, changeable, fatigable, frail, subject to be worn out, and capable of Decay, (which makes the Certainty of Death in all Animals, and in us since the Fall into an Animal Nature) does, upon that Account, and lest the continual Contraction and tensive Stress of Parts, by that Means, should spoil their Tone, and to recruit the wasted Sprits by Rest, (after tuggingall Day at the Vigilative Contraction) grow willing to give over the Drudgery, however convenient for the Uses aforesaid; Therefore being allow'd convenient Rest by his Maker, he, for the great Benefit of Refection, without which he cannot continue his Being, and for the sweetness of Ease, loosens the Reins of Vigilative Contraction; where∣upon Sensation and Promptitude to Motion (which were maintain'd by that Contraction, causing the Tension of Organs, and Compression of the Animal Spirits, as has been Mechanically demonstrated) fail by the Relaxation of those Organs, Membranes, and Vessels of the Spirits, and the consequent Expansion of the Animal Spirits; so that now only the Compression of the Atmosphere remains, which (as you see in a Gut half full of Air un∣der that Pressure) is not sufficient to convey the Page  122 Impressions with any Smartness, or cause the Ani∣mal Spirits to spring vigorously into Motion; which Decay or Failure of Sense and Motion by Relaxa∣tion, and the consequent Expansion of the Animal Spirits, is the State of Natural Sleep.

Note, That Relaxation is a necessary Conse∣quence of the Privation of Contraction, and re∣quires no Labour, but a bare Remission of that Contraction.

Note, That the Watching Part of our Lives is upheld by Force, and that Nullum violentum est diuturnum, and consequently a necessity of Sleep, and at last of Death it self.

Thus have you the true Reason of Sleeping and Watching, which will naturally, plainly, and easily solve all the Phenomena's thereof; for it is most evident from the Premises:

• 1. Why Watching and Sleeping observe a Pro∣portion between them; the being tired with one being the cause of the other.
• 2. Why Sense and Motion do fail so much in Sleep, viz. by the Relaxation of all Parts, and Expansion of the Animal Spirits.
• 3. Why they always fail together, and in like Proportion.
• 4. Why they do not wholly fail in Sleep; be∣cause the Compressure of the Atmosphere, &c. re∣mains.
• 5. Why in Sleep the Limbs are (like a Gut half full of Air) lax, limber, flaccid, and yielding all manner of Ways; because all the innumerable small Vessels that contain the Elastick Animal Spirits, are (as that half fill'd Gut I mentioned) not tightly fill'd, which if they were, would be firm and Page  123tense, as such a Gut, blown up very full and for∣cibly, is; which Vessels being all over the Body, con∣firm the whole Tone when we are awake, and the Vigilative Contraction compresses the Animal Spirits into a Steadiness, and (as it were) a kind of Solidity.
• 6. Why (as appears by Statick Demonstrations, and Experiments) we perspire more when asleep than awake; because the Pores are closed by the Vigilative Contraction, and open'd in Sleep by the contrary Relaxation, which therefore always causes free Perspiration where ever it happens, as in faint∣ing Fits, Syncopes, Leipothymies, and by Warmth, especially if moist and emollient, as in Baths, Fo∣mentations, Feet Washes, Head Washes, &c. as also when Pleasure relaxes, as in the Act of Venery, great Joy, after good Meals, or some Glasses of Wine, &c. all which cause plentiful Perspiration, because they relax, and thereby open the Pores, (as more fully appears in the following Discourse) by Reason of the Pleasure that they cause, which diverts the sensitive Soul from his Employ of Con∣traction.
• 7. Why, the Pores being open by the Relaxation, we sweat in our Sleep, if we are fill'd with Mat∣ter for it, viz.〈 in non-Latin alphabet 〉, That is, Much Sweat in Sleep argues, that much Food (or Nutriment) was taken; of which Drink is the greatest Part in Bulk, even in Sober Per∣sons. I mention this to shew the Difference in the Case of Perspiration and Sweating, for that always happens in Sleep, but not Sweat, unless the Body be well fill'd with Moisture; To shew the Cause of which Difference, will be the Business of my Tract of Animal Mechanism, if I have not hereafter an Occasion to do it in this Tract, as (I sup∣pose) I may.
• Page  1248. Why Sleep cures Colds (by opening the Pores.)
• 9. Why the Skin is more florid in Sleep; be∣cause (as has been said) it being relax'd admits the Bloud into it, which Vigilative Contraction does in good measure repel, and thereby cause the Skin to appear more white and pale, as it is, and any one may observe upon awaking.
• 10. Why the Eyes look deadish in Sleep, viz. because (as has been shewn) the Humors do not fill up the relaxed Cornea to a due Tension and Ro∣•undity, which (as was said) makes the Cornea shine, sparkle, and particularly to reflect a brisk Speck of Light, (as shining round Things must do) which Speck if Painters omit, the Eye looks deadish, therefore they should, when they have a mind to express the Deadness of the Eyes, as in Fainting Fits, Syncopes, Sleep, Death, Wanton loose Oglings of Lovers, Drunkenness, &c. omit that Speck, or rather draw it duller, wider, and discomposed in Figure, with the Pupil very large, and the Upper Eyelid falling down loosely, which would exactly express the Deadness of the Eye in all those Cases of Relaxation, in which alone it so appears. Note, That the Reason why some in such Cases see divers Colours before their Eyes, is, because the uneven Cornea variously retracts and reflects the Light, which I mention because none (that I know of) have observed the Cause.
• 11. Why People are more sleepy in warm moist Weather, viz. because the Parts are more relaxed, and the Pressure of the Atmosphere less to assist the Vigilative Contraction, to keep us in a waking State by the Compressure of the Animal Spirits: How much better therefore is a cool and dry Air, that raises the Mercury high in the Barometer, (or Weather Glass) both for Heath and Action? be∣cause it renders the Animal Spirits more power∣ful, Page  125 prompt, and flippant by the Compression. This should be observ'd by such as are to run Races alone, lift Weights, or perform any Thing that requires Strength, Vigour, or Speed; nor can I doubt, but if we had an Artificial Means to com∣press Men's Bodies in a high manner, (as by put∣ting them into convenient Cavities, and forcing Air upon them) but they would be much stronger for the Time, and thereby enabled to do Ex∣ploits beyond their ordinary Strength; which puts me in mind of several Things that confirm it very much, as Mens lifting of greater Weights in low Places, than on the top of very high Hills, where the Pressure of the Air is less to compress the Animal Spirits; The Contraction of all Parts in lifting of great Weights; The prodigious Leaps, and Swiftness of some Persons in great Frights, Terrors, &c. which mightily contract the sensile Parts, and Vessels of the Animal Spirits, by which Means they are render'd more springy and power∣ful.

  Note, That the true Cause of Strength is the Compression of the Animal Spirits, and that (probably) the Force of Muscles may some way or other depend upon't, which is not my Business to explain at present.

  Note, That it is the Membranes are primarily contracted, and the Medullary Part of the Nerves, Spirits, &c. compressed thereby by Conse∣quence.

• 12. Why the soft fleshed, and moist, are more sleepy, as Children, &c. viz. because the Compression of their Animal Spirits is not so great by Reason of the laxity of their Parts, so are they weaker for the same Reason, which tells you why littlePage  126 Men, whose Flesh is firmer, that are no bigger than Boys, are much stronger than Boys or Women of the same bigness.

• 13. Why warm and emollient Baths, Fomen∣tations, Feet or Head Washes, &c. do (as moist and warm Weather) cause Sleepiness; and indeed all Things that cause Relaxation, or incline the sensi∣tive Soul to leave off contracting, as Weari∣ness, &c. do cause Sleep.

  Note, That in dry Bodies, as old People, &c. such Emollient Baths, Fomentations, &c. with the Use of Emollient Moistners inwardly, will cause Sleep very finely, when Opium it self will not; and that Opium in such Cases should be used with such Things both internally and externally; but (which is not observ'd) the Baths, Fomentati∣ons, &c. should not be above the Warmth of Bloud, because the Heat may otherwise cause too much motion of the Bloud and Spirits, which is a great Enemy to Sleep, that consists in their Rest, and the aforesaid Relaxation of Parts, by both which co-operating, you may, and cannot fail to cause any Man to Sleep, if you can make them concur.

• 14. The same Relaxation causes the Pulse to be larger and slower in Sleep, Nocturnal Pollutions, want of due Contraction and Sensation at Sto∣mach, by which Means the Meat stays longer there in our Sleep, than when we are awake; So,
• 15. Frets, Commotions, and Perturbations of the Spirits, &c. are composed by Sleep, because the sensitive Soul (who is the Original of all motion) is at Rest, and that the Animal Spirits being ex∣panded, are nearer their absolute Rest, which consists in a full and perfect Expansion, so that there is no farther Endeavour towards Motion.
• Page  12716. Sensation being much lessened by the Ex∣pansion of the Animal Spirits upon the said Relaxa∣tion, the Sense of the Irritation of Humours is there∣by lessened, or quite taken away, whereupon all Fluxes occasioned by the Irritation of Humours, as Diarrhea's, Disenteries, Catarrhs, &c. are stopt or moderated (at least) by Sleep; Besides, that Relaxation being quite contrary to Contraction, by which those Humours are squeesed out, lets the Humours stay quietly where they are, Relaxation being more for receiving, containing, detaining, and suspending Humours in the Parts, than send∣ing them forward, as you see in a Spunge first contracted, and afterward suffered to dilate, or expand it self in a Dish that has some Water in it, which it takes into it self, and suspends till some∣thing squeeses it out by contracting it.
• 17. Therefore it is that the Spittle does not come into the Mouth in Sleep, or very little, and that People are apt to awake thirsty, tho' it is soon taken off in some measure by the Vigilative Contraction squeezing out the Spittle into the Mouth, unless there is some special Cause to the con∣trary.

• 18. For the same Reason the Menstruum of the Stomach comes but very slowly into the Stomach in Sleep, which is one Cause that Digestion goes on but slowly in Sleep.

  Note, That Digestion, and sending the Chyle out of the Stomach, depending both upon Con∣traction, they are hastned and retarded in exact Proportion, so that the Extrusion keeps equal Pace with the Digestion. How equal and duely pro∣portioned are the Works of Nature!

• 19. It is plain also from what has been Stated concerning Sleep, why Ague Fits seldom (if Page  128 ever) take People in the time of their first sound Sleep, because the Shivering is caused by a grievous Sensation of the sensile Parts, which cannot well happen in that sound Sleep, wherein there is so little Feeling by Reason of the said Relaxation; and because Relaxation opposes Contraction, by which that Shivering is promoted. Such a Re∣laxation, and Failure of Feeling thereupon, is the true Cause why Opium puts off Ague Fits, &c. So,
• 20. The Relaxation in Sleep stops Vomiting, by taking away the sense of the irritating Cause, and quieting (as I have intimated) all Motions in general; so Sleep stops Hiccoughs, Hemorrhages, Diary Fevers, &c.
• 21. Why Watching, Labour, or what impairs the Spirits, and tires the sensitive Soul, inclines us to Sleep, that is, disposes the sensitive Soul (the only Feeler of Lassitude) to give over Contract∣ing the Sensile Parts, which (as will plainly ap∣pear by and by) spends the Spirits, as Sleep by relaxing them causes a Recruit thereof.

To be short, (tho' one can hardly be too long in solving Phenomena's, which is the Proof of the Truth of a Man's Assertion) the Mechanical De∣monstration that I have made of the State of Sleep∣ing and Waking, does so evidently explicate all the Phenomena's of both, that I am even asham'd to run any farther upon such plain Matters, (so obvious are Things when the Truth is known,) and therefore (having mention'd those Circum∣stances and Effects of Sleep, that mainly concern us) I must give over, lest the World should think, that I take all my Readers to be Idiots, by using too many Words in so obvious a Thing; or, that I am no better for using them without Cause; for the Truth of this Matter seems to me to out∣shine Page  129 all the Arguments I can make for it, such Splendour does Truth shew upon the first Glimps thereof, as I take the Account I gave of Sleep and Watching to be; for the Opinions I have met concerning them were quite contrary to, or very remote from what I have stated.

1. They went quite contrary to it that said, That the Animal Spirits were expanded, and the Pores of the Brain, &c. more open (and conse∣quently more lax) in Watching, as Willis, and se∣veral others; who therefore say that Coffee, Volatile Salts, &c. are Antihypnoticks, (or good against too much Sleepiness) because they cause an Expansion of the Spirits, and open the Pores of the Brain, supposing (forsooth) that they marched up and down, and so kept the greater stir upon the false Imagination of their Roads being more open, which (as was proved) are really more close. Coffee keeps us from Sleep by drying, binding, and both Ways constringing the Vessels, as also by a wide grating Quality, which therefore does irri∣tate them to contract, besides that the Saline Par∣ticles causing an Agitation, may contribute there∣to, so that by constringing and agitating, it directly opposes Sleep, which proceeds from Relaxation and Quietness.

2. They were very remote from the Mark, that said (as Wedeli•s asserts all do) that Vapours were the cause of Natural Sleep, which bear no manner of Proportion thereto (as was shewn;) As they were also who m•dly talk'd, That the Animal Spirits, which have neither Life, Sense, Motion, or Election, did of themselves retire very knowingly to the Brain in S•eep, and left the Limbs, &c. de∣stitute of them, whereas (as has been Mechani∣cally proved) they have more Room than that at other times in 〈◊〉 Limbs, and all the sensile Parts. Page  130 But I will not argue against such senseless and precarious Absurdities; it is not worth the while, especially since the Truth is manifestly discovered: It would not have been so silly to have affirm'd the quite contrary, viz. That the Animal Spirits are forced into the soft and yielding Brain, in Watching, by the Vigilative Contraction of all the sen∣file Parts repelling them, as when Cold repels them by a strong Contraction of the Parts, and causes a Stupor or Sleep thereof (as they call it.) But what have we to do with such insufferable Trash? Therefore bidding it adieu, let us pursue our Bu∣siness.

That it is the Sensitive Soul, and nothing but it, has that Contracting Power, is evident;

1. Because it is the Original of all Motion in the Animal as such; and that nothing besides it has any Life, Perception, Motion, or Power, and therefore must rest till they are moved.

2. Because, That when the Sensitive Soul is di∣verted by intense Pleasure, from attending his Bu∣siness, immediately Relaxation follows; as in the Pleasure of the Act of Venery, by Wine, Ioy, &c. in which you have all the Effects of Relaxation, as Deadness of the Eyes, Dilatation of the Pupilla, plentiful Perspiration, Floridity of the Skin, a large Pulse, and sometimes a considerable Failure of Sense and Motion, as in the most pleasant time of the Venereal Act, Deliquiums, Drunkenness, Syncopes, or Ecstasies upon intense Pleasure, (which are very properly called Ecstasies) Leipothymies, Leipopsychies, &c. which signifie the Soul's leaving us without his Help by Contractions, which he then does not ex∣ercise, as being charm'd, and wholly taken up with Pleasure. This is the true Cause of all Deli∣quiums, &c. upon Pleasure, Ioy, &c. all which cause great Relaxations, and thereby Loss of Sense and Motion, as being its necessary Consequences.

Page  1313. Because grievous Sensation, which belongs only to the Sensitive Soul, puts us immediately out of Sleep into a Vigilative Contraction.

4. Because the Sensitive Soul can, when we are Sleepy, oppose it, by continuing the Vigilative Contraction; which proves Vigilative Contraction to be in his Power.

Note, That there is also other sorts of Leipothy∣mies, Deliquiums, &c. upon the Sensitive Soul's being over-tired, (whereof Natural Sleep is but a common and ordinary Degree, that happens of Course for our Relief) or over-born with some Fatigue, &c. as when somewhat grieves at Sto∣mach, and that it has laid about it all manner of Ways, by Vomiting, Convulsive Motions, &c. to be rid of it, till it can work no longer; whereupon it lays down the Cudgels, desists from all further En∣deavour by Contractions, yielding it self to Ease, seeing all Striving is to no Effect: So, that tho' this Deliquium, and the former, differ in their first Causes, yet do they agree in the last and immediate, viz. the Sensitive Soul's not attending his Business of Contraction, whereupon follows a mighty Re∣laxation, as appears by the Deadness (or Relaxation) of the Cornea, Dilatation of the Pupil, a great Laxity of all Parts, a large Pulse, or none, very plentiful Perspiration, Stops of Hemorrhages, and all Fluxes that require Contraction, &c. which happen both upon the Account of the great Relaxation it self, (as has been shewn) and the almost absolute Rest of all Things by the Sensitive Soul's withdrawing himself from Business, more than in Sleep it self. I therefore observing the Degrees of Sleep, &c. do Note, That (God and Nature using a due Proportion in all Things) the Sensitive Soul uses several Degrees of Relaxation, according as he is tired, and Refection is wanted: Hence it is, that Page  132 such as are much tired sleep more profoundly, that our first Sleeps are the soundest, and that Sleep gra∣dually declines in degrees (as we are recruited) till we awake; the nearer which we are, the more we dream, the state of Dreaming being a kind of Twilight between sound Sleep and Awaking, or between a full somniferous Relaxation and vigilative Contraction. And as the Sensitive Soul uses all degrees of Contraction below that of the Vigilative, till it comes to bare Compression of the Air; so it can exercise super-vigilative Contraction, (if I may so call it) that is, much higher degrees thereof than what was requisite ordinarily for a state of Vigilancy, as in Cases of Danger to the Animal, Frights, Ter∣rours, grievous Passions and Sensations; by which means the animal Spirits being more compressed than under the ordinary vigilative Contraction, Sensation grows more nice and smart, and Motion more prompt and vigorous (they always going together) for the Defence of the Animal, by extraordinary Flight, Repulsion, or otherwise. Hence it is, upon Fear, Terrour, grievous Pas∣sion, or Sensation, (which manifestly proves the Be∣ing of such an extraordinary Contraction upon such Occasions) That,

1. Perspiration sails in a yet higher degree than under bare or ordinary vigilative Contraction, as appears by infallible statick Experiments and Demon∣strations.

2. It is by reason of the said defensive Contraction, (for so I call it, because it is excited in an extra∣ordinary manner for the defence of the Animal in time of need, or great Exigence) That in Frights, Terrours, &c. our Hair, Dogs, &c. does stand on end, or more upright; 1. Because the Pores do, by that violent Contraction, strictly close about the Root of the Hair, that it cannot swag, incline, Page  133 or yield any way, by reason of its Weight, &c. as when the Skin is more lax and soft, and the Pores, wherein the Hair is fixed, more open. 2. Because (which is the main Reason) the said Contraction renders the oblique Pores more upright; as suppose the Pores and Hair do naturally stand obliquely, (as they do to carry off Wet, &c.) as in Fig. 1.

And that (a) in Fig. 1. is, by the said Contraction, brought nearer to (i), as much as is from (a) to (o), then will the Pores and Hair stand upright, as in Fig. 2. and the Skin a, o, e, i, s, contracted and brought within the prick'd Perpendiculars, whereas in Fig. 1. it excur'd beyond the Perpendi∣cular n, m, as much as is from a to o.

3. For the same Reason it is, That the Face, in grievous Passions and Sensations, as acute Pain, &c. is contorted and wrung awry, as you see in Persons that cry because of Grievances, (after the same manner as when they strive to lift up a great Weight) and that at the same time Tears, and Moisture at Nose and Mouth, are squeezed out by the same Contraction; which makes People use the Saying of Casting Snot about when Men cry. It is for the same Reason that People's Mouths water Page  134 extreamly when they are trimm'd with a bad Razor that puts them to Pain, which contracts the Parts, and squeezes out the Spittle.

4. The Pulse grows sensibly narrower and har∣der by the same Contraction.

5. It is by the Contraction upon grievous Sensa∣tion, that our Mouths water very much upon a Nausea at Stomach, because of the continuity of the Membranes of the Mouth and Stomach.

6. The same Contraction is the true Reason why People, upon Hunger (which is a grievous Sensation at Stomach) have so much Moisture (or Spittle) in their Mouths, and so much the more when they see good Victuals, and cannot have it, be∣cause the Grievance which causes the Contraction that squeezes it out, is by so much the greater. This is the cause why the Mouth waters when hun∣gry People see or smell good Victuals. By the same Contraction Moisture is squeezed out into the Oesophagus, (or Gullet) and the Menstruum into the Stomach at the same time; where (observe God's Good and Wise Providence) that Hunger which calls for Meat, at the same time provides Spittle to lubricate it for swollowing, and to help Digestion, render the Gullet slippery and disten∣sible, and causes the Menstruum to flow more abundantly into the Stomach; and all this when most needed, and that exactly in proportion to the Hunger (or grievous Sensation) that causes the Contraction.

It is well worth your nothing, That God's Wis∣dom does always cause the Want of what is neces∣sary in sensile Creatures, to be the solliciting and urging Cause for supply, that a due Proportion may be observed between the Supply and the Want; which may upon the telling of it appear so plain a Case, that it is scarce worth the mentioning; but (believe me) it is so little observ'd, (as plain Page  135 as it may seem to be) that People have, and do err extravagantly for want of noting it; which if they had noted, they could never have said that Vapours, or the retiring of Spirits into the Brain, &c. was the Cause, or Call of natural Sleep; nor feigned Menstruums to be the cause of Hunger; but would have duly considered what is mainly sup∣plied by Eating, or recruited by Sleeping, &c. and then had nothing to do but to conclude the Defect of that to have been the Cause that solicited for the Supply in proportion to the Defect: Which, if ob∣served, will most naturally and easily lead you to the true Knowledge of the Causes▪ of all Appetites in an Animal, upon a few Minutes Consideration; for want of which most plain and (one would think) very obvious Method, the deviating World has sadly puzzled it self about the Cause of Hun∣ger, Thirst, Sleep, and the like, to this day, and still is in Disputes about them, of which (tho' my advertent Reader may well prevent me, by using that natural Method) I shall (God willing) give an account in my Tract of Animal Mecha∣nism: Only note here, That I do not mean bare privative Defect, as such, to be the positive Cause▪ but that the Defect of what keeps or guards the Stomach, &c. from the Grievance, causes other Matter to grieve it, cause Hunger, &c. without which means, no Proportion can be observed be∣tween Hunger and what takes it away, or our Food.

7. The same defensive Contraction does, upon grie∣vous Sensation, as Pain, Cold, Terrour, &c. cause a Corrugation of the Scrotum, contract the Skin into little Tubercles like that of a Goose-Skin, &c.

8. By it, upon grievous Sensation, as by squeez∣ing the Nose very hard, pulling the Hair, Sand, or any such thing, in the Eye, or a Grievance by the Volatile Particles of Onions, Mustard, Horse-Radish-Roots, Page  136 &c. the Parts and Membranes about the Eyes contracting, squeeze out Tears, that what grieves the Eyes may thereby be washed away, or qualified, as much as the Tears can do it.

9. By this Contraction repelling the Bloud, the Skin grows Pale by Cold, Fear, Pain, &c. which also closing the Pores, stop Sweat, as in a moment. You'll have an account hereafter how Contra∣ction may cause Sweat by squeezing in some Cases, and stop it by shutting the Pores in other Cases.

10. It is by it that Contraction, that Fear, Cold, &c. closing the Pores, and repelling the Bloud, stanch Bleeding: So happens also a greater Con∣traction of the Pupil of the Eye by the same Cause.

11. It is the Violence of this Contraction upon Fear, Terrour, Pain, Cold, &c. closing the small Vessels of the Animal Spirits, and thereby repelling them, causes the Shivering in those Cases, by the Renitency of the elastick Animal Spirits springing back again, toties quoties, having gain'd more ela∣stick Force by the very Compression it self, which that Contraction causes; so that by reason of the dubious velitation (or skirmishing) between the repelling Contraction and the springing Spirits, hap∣pens a tremulous Motion, (as of quavering Springs;) which Shivering in Ague-Fits did formerly lead me to the Situation of the Cause of Agues (when I writ my Book De Febribus intermittentibus) in the Angustiae at the end of the Vessels, which termi∣nate in the Membranes; the grievous Sensation of which, causes all the Shivering that happens in any Case to Animals.

12. By the same Contraction, when very violent, and of the whole Body, cold Sweats happen in Pain, Fear, Terrour, &c. while it violently squeezes out the outmost, and therefore coldest Moisture Page  137 of our Bodies, as Laundresses do Water out of wet Linnen by Contortion. Thus if you dip one half of a wet cold Sheet in hot Water, wrapping the hot side within the cold, or let a warm Sheet that is contorted cool on the out-side of it, and then wring it as Women do Linnen, the Water that first exudates will be cold; for in this Case the closing of the Pores avails nothing to hinder it, as long as the expressing Force masters it; more especially in Animal Bodies, wherein the Parts are so contrived, that Humours design'd for Exoretion cannot well return, and therefore must, upon Contraction, run out▪

Hence it is that Alum, or Vitriol, which are very astringent, and therefore close the Pores, will notwithstanding cause the Mouth, or Nose, to run very plentifully with Moisture, by contract∣ing all the Membranes about the Mouth, or Nose, and thereby squeezing out the Moisture design'd to be excern'd, which cannot return, because the Parts▪ are contriv'd against the return or read∣mittance thereof; whereas Alum, or Vitriol, will stanch or stop Bloud by the same Contraction, be∣cause it may return (as not being design'd to be excern'd) either into the Arteries, and so pass by other Branches thereof, or (which is more ready and natural) keep its course into the Veins. So the two Riddles (that I have known some Proud Physicians amaz'd at, tho' but Trifles) of Alum and Vitriol causing the Spittle, &c. to come out, in∣stead of stopping it by their Astringency, and their stopping Bloud at Nose at the same time they cause the Snot, or other Humours, to run out, are unfolded.

13. It is by this mighty Contraction growing to an enormous degree, that the Animal Spirits being violently compressed, grow exceeding irrequiete, as upon Convulsions in great Pain, or very grievous Page  138 Sensation at Stomach, &c. while the sensitive Soul compressing them with mighty Force, and some∣what disorderly and unevenly, because of the Con∣fusion and Hurry he is in to relieve the Animal, they by their springiness fling up and down with great Vigour. This makes convulsive Motions have great Strength.

14. The Body under this Contraction is ma∣nifestly shrunk by measure, especially when the Sensation is very grievous, but most of all if they cause a general Convulsion; which I manifestly ob∣served in a little Bitch▪ that was convulsive all over for three Hours, and was just expiring, when I gave her the Sal Volat. Oleos. of Opium, which perfectly restored her by relaxing the Vessels.

Some may think it strange, That Nature should contrive a more nice and smart Sensation (which the Contraction of the Vessels of the Animal Spirits must cause by compressing them, &c.) in Pain, and by it; which becomes so much the more acute; whereas one would judge, That Nature would ra∣ther contrive its Ease than improve its Smart.

You are to know, That the Pain is in order to relieve the Animal, by exciting all its Powers to defend, expel, or reject the Cause; and that, without a grievous Sensation, the sensitive Soul is neither minded nor excited to do it; and the more the Pain is, the more it is stirr'd up to Self∣preservation, and (as was shewn) the more vi∣gorous do its Motions grow by the Compression of the elastick Spirits to perform that Work; so Na∣ture, not regarding the Pain (which is rather for good) as much as taking away the Cause, advan∣ces that, for this Purpose; like a wise Physician, who finding a Grievance at Stomach, not sufficient to excite effectual Vomiting, to throw away the grieving Cause, adds to the Grievance by giving a Vomit; which because (as was said) Nature is Page  139 proportionably excited to, and invigorated for Self-preservation, sufficiently sollicites and enables it, by a stronger Contraction, to reject the grieving Matter.

As the greater the Relaxation is, the more is the Rest of all Parts; and the weaker the Anim•l Spirits (because less compressed) the gentler are all Motions, (as you see in Sleep) consequently the less is the Expence of Spirits; so that in Sleep we generate more than we spend, and are there∣by recruited: So the more the Contraction is▪ the more violent is the Motion of the Heart, In∣testines, and of all Parts, and consequently the Expence of Spirits is the greater.

Therefore it can be no Wonder, That Contra∣ctions do cause great Commotions of Spirits, Diary Fevers, &c. when you consider,

• 1. That the sensitive Soul is, by the grievous Sen∣sations, &c. that cause them, put upon a great Fret, Concern, and Hurry, to defend the Animal, and lays about him all manner of ways for Self∣preservation.
• 2. That the Animal Spirits are, by means of great Compression caused by the defensive Contra∣ction, in a very forcible Springiness, which causes all the Actions that are continual, involuntary, and of course, to be perform'd with great Violence, proportionable to its compressed Elasticity. Be∣sides that,
• 3. The Systoles of the Heart are o•tener repeated. All which conspire to cause greater Commotions upon grievous Sensations, whereby Diary Fevers, &c. are caused, which are easily and naturally cured by Sleep, or Relaxation, at present compose and quiet those Perturbations. Who knows (tho' it is not my Business to discuss it at present) but that the Contractions in the cold Fits of Agues, have a great Page  140 hand in causing the hot ones? How otherwise should Opium, by only taking away the grievous Sensation of the cold Fits, take off, or prevent the hot Fits also? But of this, in my often-mentioned Tract, (though not so often as it grieves me that it is not published.).

How reasonably may we now expect, That pleasant Sensation may cause quite contrary Ef∣fects to that of grievous Sensation? viz. Relaxa∣tion, and all its Effects, (which have been in some measure enumerated in the Case of Natural Sleep in this Chapter) viz. Satisfaction, Composure of Frets and Commotions; as of diary Fevers, hysterick Fits, &c. Perspiration, quieting of Vomitings, Hiccoughs, &c. lessening of Feeling, and consequently a stop and moderation of all Fluxes that depend upon Ir∣ritation of Humours, as Diarrhea's, Dysenteries, Ca∣tarrhs, Vomitings, Driness of the Mouth, (as in Sleep, for want of the Contraction to squeeze the Spittle out of the Glandules into the Mouth) Nocturnal Pollutions, &c. But of the Nature and Effects of Pleasure, you'll find more in the next Chapter.

Besides the Vigilative and Defensive Contractions, (which seem to be Things of course upon Waking and Grievances) the sensitive Soul has a Contraction at Will, as that of the Pupilla, when an Animal is intent upon Seeing; of the Tympan, when intent upon Hearing; of the Musoles of the Legs, when intent upon Walking; and so of all the Muscles of the Body, which I call Intentiv• Contraction, that he can perform either along with, or without the o∣ther Contractions, or without any great degree there∣of, as when one is considerably relaxed with the Pleasure of Wine, very good News, &c. nay, some∣times even in Sleep, as is manifest by the Noctam∣•uli, (or such as walk in their Sleep) and such as Page  141 speak, strike, &c. while asleep: And as the De∣fensive Contraction does all it can in our Defence, without the Direction of the Will, as in Vomiting, Sneezing, Purging, &c. upon sensible Irritation; so this Intentive Contraction does all it can to the same Purpose, by the Direction and Dictates there∣of.

Note, That in•ensile growing Things that do not move, as Trees, &c. have none of these Con∣tractions, but what happens by Cold, and Compres∣sion of the Atmosphere, which are sufficient it seems for Nutrition, but not for Sense and Motion; it follows, That in compleat Syncopes, when the sensitive Soul gives over all Contractions, that we are much in the state of a Plant.

All those three Contractions, viz. the Vigilative, Defensive, and Intentive do, because they promote Motion, and cause it more or less, (as you find the Vigilative causes much more of it than Sleep, and the Defensive more than that, &c.) spend the Spirits, cause Weariness, &c.

The Vigilative Contraction does of it self, with∣out any considerable Grievance or Labour, that is, without the Denfensive or Intentive Contraction, tire the sensitive Soul in about 16 Hours: Hence it is that the idlest Person, that is most free from Care, Trouble, or Pain, cannot well hold out without the Recruit of Sleep any longer.

The Defensive Contraction, or that of Grievances, being added to the Vigilative Contraction, the Spirits are faster spent, and the Person tired pro∣portionably sooner, according as the Grievance is more or less; and consequently the Endeavours of the sensitive Soul to be rid thereof.

Page  142To both which Contractions, (viz. the Vigilative and Defensive) if you add the Intentive, (or La∣bour) then are you sooner and more tired than by only those two former Contractions; for this last Case is labouring in Pain, (or under a Grievance) which notoriously tires Man or Beast sooner than ordinary: The direct contrary to which, is sleep∣ing soundly and sweetly, without Trouble, Pain, or Dreams; for a dreaming Condition has too much of the vigilative Contraction in it, to be pure Relaxation and Recruit.

Now according as these Contractions are, or are not added one to another, we are sooner or later before we are tired, (speaking generally, and not considering Custom and Habit, which concerns us not.)

You see that all the three Contractions con∣ourring, do soon and sadly tire us, that no two of them tire us as much as the three together; that i•, neither the Vigilative and Defensive, without the Intentive; nor the Vigilative and Intentive, without the Defensive; and the Vigilative alone least of all: Yet allowance must be made for the Intensness of the Defensive and Intentive; for either of these two being very intense, may tire as much as both, in a moderate degree: Thus a Man may be tired with violent Labour in four Hours, tho' not in Pain as much as one that moderately labours in some small Pain for the same time.

Observe, That we recruit in eight Hours (gene∣rally speaking) as much by relaxation in Sleep, as we spend by vigilative Contraction in sixteen: I take the Reason of that to be, That Relaxation widening all the Passages of the Body, the Nutri∣ment is admitted into them more fully and freely, Page  143 as the Bloud is into the Skin in Sleep, and all Relaxa∣tions, which cause an Efflorescence thereof in those Cases. Hence it is that we are so much recruited and nourished in Sleep; that Children grow more than others proportionably; that Relaxers cause the Breasts, &c. to grow.

Note, What a mighty Restaurative Relaxation is▪ By its help, for eight Hours in twenty four, we can watch all, and labour most of the other sixteen, all the days of our Life: It follows, That if we could any way half relax the vigilative Contraction while we Labour, take a Iourney, or the like, that we might perform prodigiously, without being •ired. Hence it is, That because Pleasure (as has been in∣timated relaxes, as Grievances contract, (of which you may expect farther Proof in the next Chapter) that such as work, or travel, pleasantly diverted all the time, are tired very little or nothing in a long time; and that some will dance whole Night• with sweet Musick, and agreeable beloved Com∣pany, without being so much tired, as they would be if they us'd the same Motions for a quar∣ter of the time without either of the pleasant Diversi∣ons. The like is to be said of any other Pleasure, as drinking a good Glass of generous Wine every half hour, or so often as to continue the sense of its Pleasure at Stomach all the time they labour or tra∣vel; for 'tis a vulgar Errour, (tho' the universal Sentiment of Mankind, both Learned and Un∣learned) That Wine, Cordials, &c. do comfort, elevate, and excite the Spirits, (as 'tis call'd) by adding their Spirits to, or joining them with ours; whereas it is only by causing a pleasant Sensation, particularly at Stomach: For which Paradox, I am obliged (tho' in great haste to come to the Ex∣plication of Opium) to give my Reasons, which are as follows, viz.

Page  144
• 1. It cannot be imagined how a sensitive Crea∣ture, as such, can conceive any Comfort, or be sensible thereof, but by Sensation: To say he is comforted, and not sensible of the Comfort, is a Contradiction; for Comfort, as such, belongs to a perceiving Being; and an Animal, as such, per∣ceives nothing but by the Senses; and therefore there can be no Comfort but by pleasant Sensation; nay, as such it is his Comfort: So Musick, pleasant Sights, Odours, and agreeable Objects of all the Senses, are comfortable, because pleasant. I hope that none will say, That Musick, Sights, good News &c. (which highly comfort) have any Spirits to add to ours: The truth is, That God and Nature have given us our Senses for that end, and present Refection in Cases of Faintness, Depression of Spirits; And what more proper to convey Comfort to us, than what is sensible of it?
• 2. It is another thing to add by way of Nutri∣tion to our Spirits, (which are insensible Things, and therefore never properly comforted any more than a Plant, that is nourished as well as they:) But the sensitive Soul being pleased, must needs con∣ceive Satisfaction, Comfort, Ioy, &c. How he can be pleased when sensible of nothing, I know not; nor how he can be comforted without being first pleased, nor how pleased but by Sensation.
• 3. The Essence of Animal Comfort does not con∣sist in having many Spirits; for one in most grie∣vous Pain and Misery, by which he is much dis∣comforted, cast down, depressed in Spirit, &c. may have great plenty of Spirits; and one that has not half as many, highly comforted, by plea∣sing Objects of Sense, good News, &c.
• 4. If we staid for Comfort by a Meal of Meat, &c. till it added to our Spirits, we might stay long enough; nay, if we staid for Comfort till Page  145 we found it by that Addition, we should never find it; for we cannot in that case find what we do not feel: We possibly, after two or three days eating and drinking, may find our selves stronger; but (after all) suppose us in very great misery at the same time, Where's the Comfort of it, when the Spirits are otherwise depressed by Pain, ill News? &c.
• 5. Hunger is a grievous Sensation at Stomach; which is cured, and we comforted, by causing a pleasant Sensation by Meat, Wine, &c. instead thereof; and not by adding Spirits, which is a great Mistake. It is true indeed, that we are comforted, but it is most manifestly by pleasing the exquisite Sensation at Stomach, which God has placed there for that End: Hence it is that all Cordials must be pleasing to the Stomach, or else they are no Cordials; and that Wine, and all such Things as please the Stomach, are apt to take away much of the Sharpness of Hunger, for a time at least.
• 6. How should Wine, which has a great Aci∣dity in it, and so very good for Digestion, cure a canine Appetite, which is a grievous Sensation, but by causing a pleasant one in its room, by which means the grievous Sensation is taken off? For Plea∣sure and Grievance, (or Displeasure) which are Contraries, cannot be in the same Subject at one time. Thus it is that Opium takes off Hunger, canine Appetite, &c. But of this hereafter.
• 7. How should a Quart of Wine; drank in a minute or two, have all the comfortable Effects of Wine in a quarter of an hour while it is at Stomach, if it were to stay for this Comfort till it added Spirits to ours, since the matter of Effluvia, or Fumes passing into the Rloud, is disproved?
• Page  1468. Why should our Comfort be so great while it is at Stomach, and none by that time it is got into the Bloud, but that the Stomach being very sensile, the Spirits of the Wine do highly please by their Agreeableness thereunto? It matters not whether it had Spirits or no, so it caused a pleasing Sensation; for a Draught of Water in a high Fever, and when we are very faint with Thirst, very much comforts us without any Spirits, as does a Venison-Pasty a hungry Person, by agreeable Sensation taking off the grievous Sensation (called Hunger) and all its consequent Faintness, &c. before it can add any Spirits by Nutrition.
• 9. What need we seek any farther? Do not we find a pleasing Sensation at Stomach, when we are comforted with any thing, and the Comfort to bear a Proportion to the Pleasure?
• 10. Are not we prompt, blithe, gay, and brave, while the Wine is at Stomach? And very often fit for nothing, dull, heavy, mopish, &c. by that time it is got into the Bloud?

Therefore we may safely conclude, That the Spirits of the Wine do comfort us, by causing a pleasing Sensation, and not by adding its Spirits to ours, according to the settled Sentiment of the World, that is not yet arrived to the Learning or Knowledge why the most common Cordial com∣forts them. What Spirits has a Grain of Opium, while at Stomach, to add to ours; or can it add, if it had them? Yet no Wine comforts us as much as Opium, because it pleases us so much, (as was and will be yet much more fully shewn.)

Note, That besides what was said of the Grie∣vousness of the three Contractions, to ti•e the animal or sensitive Soul, he is much deprest and cast down, upon the Perception of Grievances, as Hunger, Pain, &c. Because they, 1. Affect him with Grief Page  147 and Displeasure, and consequently with Discomfort, Anxiety, &c. because of the very Dolour. 2. With Care and Solicitude how to be rid of it. 3. With the Toil of Defensive Contraction to endeavour it.

All which causes Melancholy, Depression of Spirits, Pusillanimity, Perturbations, Frets, Discomposure, Dis∣satisfaction, Anxiety, Solicitude, Peevishness, Discom∣posure, Discomforts, Listlesness, &c. as you see in such as are Hungry, or in Pain; to which if you add the Fatigue and Effects of the Defensive Con∣traction, and the Intentive, as far as it is exercised for Self-preservation in this Case, you may (obser∣ving what has been said) easily solve all the Pheno∣mena's of grievous Sensation, and as easily conclude what must be the Phenomena's and Effects of plea∣sant Sensation, by the Rules of Contraries, viz. Sa∣tisfaction, good Humour, Ease, Comfort, Ovation of Spirits, Relaxation, &c. of which we are going to speak.