Certain physiological essays and other tracts written at distant times, and on several occasions by the honourable Robert Boyle ; wherein some of the tracts are enlarged by experiments and the work is increased by the addition of a discourse about the absolute rest in bodies.

A PROEMIAL ESSAY, WHEREIN, With some considerations touching EXPERIMENTAL ESSAYS in General, Is interwoven such an Introduction to all those writ∣ten by the Author, as is necessary to be perus'd for the better understanding of them.

I Know not, Pyrohilus, whether what you will meet with in the ensuing Discourses will prove worthy of your taking notice of it: Yet I dare tell you, that if all my Endeavours to serve you were not Duties, I should think I might deserve your Thanks for venturing to write them for your sake. For I am suf∣ficiently sensible both how unlearned I am, and in how learned an Age I presume to write: Nor has the great number of those escap'd my Observation, who finding it a much easier task to censure Experimental Composures than to write such, endeavour to acquire the Title of Ju∣dicious, by condemning all things that themselves have not written, or thought on. And indeed, Pyrophilus, I had besides these, so many other discouraging Considerations in my Eye, whilst I was setting down the following Essays, that I should scarce have prosecuted a Design so full of trouble, and so unlikely by its success to make amends for

it, if I had thought it free for the securing of my own Quiet and Credit, to suppress Observations which might prove serviceable to you, who having sufficiently convers'd with Books, are now desirous to begin to converse with Things themselves. But I must confess, I look upon Experimen∣tal truths as Matters of so great concernment to Mankind, that in spight of the just sense I have of my own Disabili∣ties, I am deterr'd from complying with those Inclinati∣ons and Motives that endear silence to me, by consider∣ing the Fate of him, who though he had less entrusted to him than any of his Companions, was yet severely punisht for burying his single Talent. And though, Pyrophilus, I could not without such reluctancy resolve to write, yet I found it much more uneasie to resolve to write so soon: For I could not but consider, that being yet but very young, not only in Years, but, what is much worse, in Ex∣perience, I have yet much more need to learn, than abili∣ty to teach; and I consider'd too, that after a man is grown somewhat acquainted with things themselves, and has taken some general notice of the Cognations, Diffe∣rences, and Tendencies of their Properties, he may every day so much improve his Knowledge, that I am apt to think, that if God should be pleas'd to protract my Life a few years longer, I shall at the end of them be able to look upon what I have hitherto written with Pity, if not with Blushes. And I have often observ'd, that it is wont to happen in the productions of the Mind, as in those of the Body. For as those that apply themselves to Procre∣ation too young, and before they have attain'd to their full vigour and strength, do generally both hinder their own growth, and become the Parents but of weak and short-liv'd Children; so they that too early, and before their Judgment and Experience be fully ripe, addict themselves to write Books, do commonly both hinder their own Proficiency in Knowledge, and write but imma∣ture,

and therefore seldom lasting Treatises. Nor should I, Pyrophilus, have ever prevail'd with my self to present you so early these Discourses, since by keeping them lon∣ger by me, I might easily by second Thoughts, and fresh Experiences be enabled to correct and enrich them, did not the frequent and dangerous distempers to which my very sickly Constitution has of late render'd me obnoxi∣ous, make me justly doubt, whether or no, if I should long forbear to write, Death would not sooner come than the expected Maturity of Age and Judgment. And though I had no such Consideration to move me to make hast to tender to you the ensuing Discourses, yet this would suf∣fice to engage me to present them you with all their pre∣sent defects; that if I should keep them till I can make them less unworthy of you, I must keep them till you are grown past the need of them.

And now that I have told you, Pyrophilus, both why I have written the ensuing Discourses, and why I keep them not by me long enough to present them you with fewer Imperfections, I suppose you will expect that I should next tell you why I have cast them into Essays, rather than into any other form. To satisfie you about this particu∣lar, Pyrophilus, I must freely acknowledge to you, that it has long seem'd to me none of the least impediments of the real advancement of true Natural Philosophy, that men have been so forward to write Systems of it, and have thought themselves oblig'd either to be altogether silent, or not to write less than an entire body of Physiology: for from hence seem to have ensu'd not a few Inconve∣niences.

And first, when men by having diligently study'd either Chymistry, Anatomy, Botanicks, or some other particular part of Physiology, or perhaps by having only read Au∣thors on those Subjects, have thought themselves thereby qualify'd to publish compleat Systems of Natural Philo∣sophy,

they have found themselves by the nature of their undertaking, and the Laws of Method, engag'd to write of several other things than those wherein they had made themselves Proficients, and thereby have been reduc'd, either idly to repeat what has been already, though per∣haps but impertinently enough, written by others on the same Subjects, or else to say any thing on them rather than nothing, lest they should appear not to have said something to every part of the Theme which they had taken upon themselves to write of.

In the next place, the specious and promising Titles and comprehensive Method of these Systems have been often found to perswade unwary Readers, that all the parts of Natural Philosophy have been already sufficiently expli∣cated, and that consequently it were needless for them to put themselves to trouble and charges in making further Enquiries into Nature, since others having already suffici∣ently made it their business to investigate and explicate Physiological Truths, our business needs now be no more than to learn what they have taught, and thankfully to acquiesce in it.

Nor has the Systematical way of writing been prejudi∣cial only to the proficiency of some Readers, but also to the reputation of some Writers of Systematical Books. For it not unfrequently happens, that when a Writer, to vent some few peculiar Notions or Discoveries of his own, presumes to write a whole body of Philosophy, what is truly his own, though excellent in its kind, is either lost in the Crowd of the things he has borrow'd from others, and so comes to be over-look'd, or at least not sufficiently ta∣ken notice of, by the Reader; or else the unwelcome, and yet in such Composures scarce evitable, Repetition of many things that others had I know not how often written before, occasions the laying aside of the whole Book, as a Rhapsody of trite and vulgar Notions, scarce worth the

perusing: and by this means the Author often loses the Reputation of his peculiar Notions, as well as the Reader the benefit of them; and that which would have made an excellent and substantial Essay, passes but for a dull and empty Book.

But the worst Inconvenience of all is yet to be men∣tion'd, and that is, That whilst this Vanity of thinking men oblig'd to write either Systems or Nothing, is in re∣quest, many excellent Notions or Experiments are by so∣ber and modest men suppress'd, because such Persons being forbidden by their Judgment and Integrity to teach more than they understand, or assert more than they can prove, are likewise forbidden by Custome to publish their Thoughts and Observations, unless they were numerous enough to swell into a System. And indeed it may be doubted whether the Systematical Writers have not kept the world from much more useful Composures than they have presented it with. For there are very few men, if any at all, in the world, that are enrich'd with a compe∣tent stock of Experiments and Observations to make out clearly and solidly, I say not all the Phaenomena of Nature, but all those that belong to Chymistry, Anatomy, or any such considerable subordinate Doctrine of Physiology. And those very men that are diligent and judicious enough to study prosperously any of those parts of Phy∣siology, are oblig'd to spend so much time in the accurate Prosecution of that, and are wont to be thereby made so wary, and so thorowly acquainted with the difficulty of Physiological Investigations, that they will least of all men be forward to write Systems.

And what I say, Pyrophilus, of the inconveniences that have hitherto been observ'd to flow from mens forwardness to write entire bodies of Philosophy; may be in its degree appli'd to the practice of those that pretend to give us compleat accounts of Chymistry, or almost (I say almost)

any other considerable and comprehensive part of Natural Philosophy: Though I deny not, that in such attempts which are much less difficult than the former, some Men have done Mankind considerable service, though they have not fully perform'd what the Titles of their Writings seem to promise. Nor am I so rigid as to be unwilling that from time to time some very knowing Writer should publish a System of Physiology, or any part of it, accord∣ing to the best Authors and Observations of that time: For such a Work may be useful, partly, for the instructing of Youth in Schools and Academies; and partly, that men may have from time to time an Inventory of what hath been already discover'd, whereby the needless labour of seeking after known things may be prevented, and the progress of Mankind as to Knowledge might the better appear. But then it is to be wish'd that such Writings were not publish'd but by very intelligent Persons, nor till some considerable improvement have been made in Know∣ledge since the last work of that Nature. Nor would I be thought to disallow such Writings of very Learned Men, as though they may bear very general Titles, yet are not publish'd by their Authors as compleat Bodies or Systems of Physiology, but rather as general Principles (almost like the Hypotheses of Astronomers) to assist men to ex∣plicate the already-known Phaenomena of Nature. For of such kind of Writings, if their Authors be (as for the most part they are) subtle and inquisitive men, there may be very good use, not so much by their gratifying the Intellect with the plausible account of some of Natures Mysteries; as because on the one side their Writers, to make good their new Opinions, must either bring New Experiments and Observations, or else must consider those that are known already after a new Manner, and thereby make us take notice of something in them unheeded before; and on the other side, the curiosity of Readers, whether they

like or disapprove the Hypothesis propos'd, is wont to be thereby excited to make trial of several things, which seeming to be Consequences of this new Doctrine, may by their proving agreeable or repugnant to Experiment ei∣ther establish or overthrow it.

And that you may know, Pyrophilus, what kind of Wri∣tings I mean, I shall name to you the Learned Gassendus his little Syntagma of Epicuru's Philosophy, and that most ingenious Gentleman Mons^r Des-Cartes his Principles of Philosophy. For though I purposely refrain'd, though not altogether from transiently consulting about a few Particulars, yet from seriously and orderly reading over those excellent (though disagreeing) Books, or so much as Sir Francis Bacon's Novum Organum, that I might not be prepossess'd with any Theory or Principles till I had spent some time in trying what Things themselves would incline me to think; yet beginning now to allow my self to read those excellent Books, I find by the little I have read in them already, that if I had read them before I began to write, I might have enrich'd the ensuing Essays with di∣vers truths which they now want, and have explicated di∣vers things much better then I fear I have done. But of such Writers the number is yet (and will I fear always be) so small, that I shall not need to make many Exceptions when I treat of the usefulness of writing Books of Essays, in comparison of that of writing Systematically: Or at least, Pyrophilus, whilst I presume not to judge of other mens abilities, I hope it may be lawful for me to confess freely to you concerning my self, that I am very sensible of my being far from having such a stock of Experiments and Observations, as I judge requisite to write Systemati∣cally; and I am apt to impute many of the Deficiencies to be met with in the Theories and Reasonings of such great Wits as Aristotle, Campanella, and some other celebrated Philosophers, chiefly to this very thing, that they have too

hastily, and either upon a few Observations, or at least without a competent number of Experiments, presum'd to establish Principles, and deliver Axioms. For it very rare∣ly otherwise happens, than that Theories that are ground∣ed but upon few and obvious Experiments are subject to be contradicted by some such Instances as more free and diligent Enquiries into what of Nature is more abstruse, or even into the less obvious Qualities of things, are wont to bring to light. I remember, that being once at Leyden, I was brought to the Top of a Tower, where in a darken'd room (such as is now used in many places to bring in the Species of external Objects) a Convex glass, apply'd to the only hole by which light was permitted to enter, did pro∣ject upon a large white sheet of Paper, held at a just di∣stance from it, a lively representation of divers of the chief Buildings in the Town, all which upon the admission of more light into the room, by opening the Window, did immediately disappear. And methinks, Pyrophilus, that in divers of the Philosophical Theories that have been formerly applauded, something not unlike this may be easily observ'd: for though, whilst they are look'd on with such a weak and determinate degree of light, they may appear very artificial and well-proportion'd Fa∣bricks, yet they appear so but in that twilight, as it were, which is requisite to their conspicuousness. For if but a full light of new Experiments and Observations be freely let in upon them, the Beauty of those (delightful, but Phantastical) structures does immediately vanish.

And truly, Pyrophilus, if men could be perswaded to mind more the Advancement of Natural Philosophy than that of their own Reputations, 'twere not methinks very uneasie to make them sensible, that one of the considera∣blest services that they could do Mankind, were to set themselves diligently and industriously to make Experi∣ments and collect Observations, without being over-for∣ward

to establish Principles and Axioms, believing it un∣easie to erect such Theories as are capable to explicate all the Phaenomena of Nature, before they have been able to take notice of the tenth part of those Phaenomena that are to be explicated. Not that I at all disallow the use of Reasoning upon Experiments, or the endeavouring to dis∣cern as early as we can the Confederations, and Diffe∣rences, and Tendencies of things: For such an absolute suspension of the exercise of Reasoning were exceeding troublesome, if not impossible. And as in that Rule of Arithmetick which is commonly called Regula falsi, by proceeding upon a conjecturally-supposed Number, as if it were that which we enquire after, we are wont to come to the knowledge of the true number sought for: so in Physiology it is somtimes conducive to the discovery of truth, to permit the Understanding to make an Hypothe∣sis in order to the Explication of this or that difficulty, that by examining how far the Phaenomena are, or are not, ca∣pable of being salv'd by that Hypothesis, the Understand∣ing may even by its own Errors be instructed. For it has been truly observ'd by a great Philosopher, That Truth does more easily emerge out of Error than Confusion. That then that I wish for, as to Systems, is this, That men in the first place would forbear to establish any Theo∣ry, till they have consulted with (though not a fully com∣petent number of Experiments, such as may afford them all the Phaenomena to be explicated by that Theory, yet) a considerable number of Experiments in proportion to the comprehensiveness of the Theory to be erected on them. And in the next place, I would have such kind of superstructures look'd upon only as temporary ones, which though they may be preferr'd before any others, as being the least imperfect, or, if you please, the best in their kind that we yet have, yet are they not to entirely be acquiesced in, as absolutely perfect, or uncapable of im∣proving Alterations.

It were very possible, Pyrophilus, to let you see that all that has been said to recommend to you that form of Wri∣ting which (in imitation of the French) we call Essayes, is but a part of what may be pertinently said to the same purpose. But because this Introductory Discourse it self is to be but an Essay, not a Book, I dare not long insist upon the Advantages of this sort of Discourses. Only because I think that if I could engage you, Pyrophilus, and such other ingenious Persons, to cast their Physiological Observations and Reflexions into Experimental Essayes, I should thereby do real Learning no trifling service, by bringing so useful a way of writing into the request it de∣serves; Upon this consideration, I say, I must beg leave to represent to you this great Conveniency of Essayes, That as in them the Reader needs not be clogg'd with tedious Repetitions of what others have said already, so the Wri∣ter, having for the most part the Liberty to leave off when he pleases, is not oblig'd to take upon him to teach others what himself does not understand, nor to write of any thing but of what he thinks he can write well. And if such Essayes be but as they should be competently stock'd with Experiments, 'tis the Readers own fault if he be not a Learner by them: for indeed when a Writer acquaints me only with his own Thoughts or Conjectures, without enriching his discourses with any real Experiment or Ob∣servation, if he be mistaken in his Ratiocination, I am in some dang••r of erring with him, and at least am like to lose my time, without receiving any valuable Compensation for that great loss: but if a Writer endeavours, by deli∣vering new and real Observations or Experiments, to cre∣dit his Opinions, the Case is much otherwise; for let his Opinions be never so false, his Experiments being true, I am not oblig'd to believe the former, and am left at liberty to benefit my self by the later; and though we have er∣roneously superstructed upon his Experiments, yet the

foundation being solid, a more wary builder may be very much further'd by it in the erection of more judicious and consistent Fabricks: such a Writer, if I be not wanting to my self, will certainly teach me useful Truths, and if it be not my fault, he can lead me into no errors; and oftentimes the very Experiments that he delivers, besides that they may be applicable to many other purposes unthought of by him, may be either sufficient or at least helpful to the very discovery of the erroneousness of the Opinions they are alledg'd to countenance: and I make account that a man that gives me, together with his conjectures (though erroneous) in matters of Physiology, some noble Experi∣ment or Observation by which he pretends to verifie them, does me no greater injury than Galileo upon his first Invention of the Telescope would have done an Astrono∣mer, if he had told him, that he had discover'd in Heaven those imaginary new Stars which a late Mathematician has fancy'd himself to have descry'd there, and at the same time had made him a Present of an excellent Telescope, with expectation that thereby the Receiver should be made of the Giver's Opinion; for by the help of his In∣strument the Astronomer might not only make divers use∣ful Observations in the Sky, and perhaps detect new Lights there, but discern also his mistake that gave it him.

After what has been said, Pyrophilus, of the Usefulness of experimental Essays, we must proceed to say something concerning the Manner of writing them: but because you will also expect to receive some account of the ensuing Discourses, I shall not treat of those two Subj••cts apart, but, in discoursing of the following Essays, shall take occa∣sion to acquaint you with part of my thoughts concerning such kind of Composures in general, the other Considera∣tions belonging to the same Subject being already upon several Occasions dispers'd among, and to be met with in, the ensuing Discourses themselves.

And first, as for the style of our experimental Essays, I suppose you will readily find that I have endeavour'd to write rather in a Philosophical than a Rhetorical strain, as desiring that my expressions should be rather clear and significant, than curiously adorn'd: For, to a subject of the serious and important Nature of Physiology, that say∣ing may unquestionably be appli'd, Ornari res ipsa negat, contenta doceri. And certainly in these Discourses, where our design is only to inform Readers, not to delight or perswade them, Perspicuity ought to be esteem'd at least one of the best Qualifications of a style, and to affect need∣less Rhetorical Ornaments in setting down an Experi∣ment, or explicating something abstruse in Nature, were little less improper than it were (for him that designs not to look directly upon the Sun it self) to paint the Eye-glasses of a Telescope, whose clearness is their Commen∣dation, and in which even the most delightful Colours cannot so much please the eye as they would hinder the sight. And that it may not be suspected, that those that would not have it requisite to imploy a florid style in treating of Philosophical Subjects, do but in their own excuse deny the necessity of such Rhetorical Embellish∣ments as they are not able to afford their Composures, give me leave to subjoyn, that it was not an unpolish'd Naturalist, but that Prince of Orators, Cicero himself, who made this studious Declaration, Omne (says he) quod de re bona dilucidè dicitur, praeclarè mihi dici videtur: istius∣modi autem res velle ornatè dicere, puerile est; planè autem & perspicuè expedire posse, docti & intelligentis Viri. But I must not suffer my self to slip unawares into the Com∣mon place of the unfitness of too spruce a style for serious and weighty matters; and yet I approve not that dull and insipid way of writing which is practis'd by many Chy∣mists, even when they digress from Physiological Subjects: for though a Philosopher need not be sollicitous that his

style should delight its Reader with his Floridnesse, yet I think he may very well be allow'd to take a Care that it disgust not his Reader by its Flatness, especially when he does not so much deliver Experiments or explicate them, as make Reflections or Discourses on them; for on such Occasions he may be allow'd the liberty of recreating his Reader and himself, and manifesting that he declin'd the Ornaments of Language, not ou•• of Necessity, but Discretion, which forbids them to be us'd where they may darken as well as adorn the Subject they are appli'd to. Thus (to resume our former Comparison) though it were foolish to colour or enamel upon the glasses of Tele∣scopes, yet to gild or otherwise embellish the Tubes of them, may render them more acceptable to the Users, with∣out at all lessening the Clearness of the Object to be look'd at through them.

And as for Exotick Words and Terms borowed from other Languages, though I expect that Persons not con∣versant in the Philosophical Composures written (especi∣ally of late) in our Language will be apt to suspect me for the willing Author of divers new Words and Expressions, yet as for you, Pyrophilus, who peruse other then Moral, Theological, and Historical Books in English, and find how much use is made in them of Exotick Terms, I hope you will find that I have not at all affected them, but have ra∣ther studiously declin'd the use of those which Custom has not render'd familiar, unlesse it be to avoid the frequent and unwelcome Repetition of the same word, (so trou∣blesome to the Ear, and so much forbidden by Orators) or for some peculiar significancy of some such Word, whose Energy cannot be well express'd in our Language, at least without a tedious Circumlocutioo. And in such cases, Pyrophilus, I suppose a Writer may be allow'd to use Exotick Terms, especially when Custom ha•• not only Denizon'd them, but brought them into request. For as in the Fashions of Clothes, though perhaps Fools begin

them, yet Wise men, when they are once generolly re∣ceiv'd, scruple not to follow them, because then obsti∣nately to decline them would be as ridiculously singular as at first it would have been to begin them: so in Exo∣tick Words, when Custom has once made them familiar and esteem'd, scrupulous••y to decline the use of them may be as well a fault, as needlesly to imploy them: For it is not the Use but the Affectation of them that is unworthy a Philosopher. And from the latter of those I hope I have kept my self far enough: For I should think my self guilty of a very Childish vanity, if the use I made of Languages were so to write as to be the less understood. But besides the unintentional deficiencies of my style, I have knowingly and purposely transgress'd the Laws of Oratory in one particular, namely, in making sometimes my Periods or Parentheses over-long: for when I could not within the Compass of a regular Period comprise what I thought requisite to be delivered at once, I chose rather to neglect the Precepts of Rhetoricians, than the mention of those things which I thought pertinent to my Subject, & useful to you, my Reader. And for this fault, Pyrophilus, since I have made my self guilty of it but for your sake, I think I ought to obtain your pardon at least as easily as my own, since barely to keep you from losing any thing that I conceiv'd might be serviceable to you, I knowingly ex∣pose my style to be censur'd as disproportionate to it self.

The next thing, Pyrophilus, of which I am to give you an account, is, why I have in the ensuing Essays deliver'd many Experiments and Observations, which may seem slight and easie, and some of them obvious also, or else per∣haps mention'd by others already. To satisfie you about this, I must inform you that many of the Particulars which we are now considering, were in my first Design collected in order to a Continuation of the Lord Verulam's Sylva Sylvarum, or Natural History. And that my intended

Centuries might resemble his, to which they were to be annex'd, it was exquisite that such kind of Experiments and Observations as we have been newly speaking of, should make up a considerable part of them. And indeed it were to be wish'd, that such inquisitive Persons as can∣not be at the Charge, or have not the opportunity, of ma∣king new Experiments, would busie themselves, as they have opportunity, in industriously collecting and carefully setting down the Phaenomena to be met with without the Assistance of new Experiments, especially such particulars as seem either to be of moment in order to the hinting or Confirmation of some Considerable Truth, or to the Dete∣ction of some Applauded Error, or else to have bin, though obvious enough, yet little taken notice of. For I am con∣fident that very much may be done towards the Improve∣ment of Physiology by a due Consideration of and reflexion on the obvious Phaenomena of Nature, and those things which are almost in every bodies power to know, if he please but seriously to heed them; and I make account that attention alone might quickly furnish us with one half of the History of Nature, as well as industry is requisite, by new Experiments, to enrich us with the other. And therefore I confess I think my self beholding to him that first makes me take notice of what I might easily have known, but heeded not before; it not seldom happening, that we are prejudic'd by, though we do not complain of that ignorance from which we might relieve our selves, if we did but diligently turn our eyes to the Observations wherewith even neighbouring and familiar Objects would, if duly consulted, present us. But I digress, and therefore must step back into the way, and tell you, that the reasons why I first design'd the Narrative of what I had try'd and observ'd for a Continuation of Sir Francis Bacons Natural History, you will meet with in my Preface to that specimen of the intended Continuation, which I have given in those

of my Essays that treat Of Promiscuous Experiments: and the reason why I have since declin'd that succinct way of Writing, is, for the sake of Pyrophilus, that I might have, in a more free and uncircumscribed way of discoursing, a greater Liberty to insist on and manifesf the Reasonable∣ness of such Animadversions as I thought seasonable for a Person, who, though a great Proficient in the other parts of Philosophy, is but a Beginner in Experimental Learn∣ing. And the second Reason why I have often made use of seemingly slight Experiments, is, because such are more easily and cheaply try'd, and they being alledg'd for the most part to prove some Assertion, or credit some Admo∣nition, I thought their Easiness or Obviousness fitter to recommend them, than depretiate them; and I judg'd it somewhat unkind, or at least indiscreet, to refer you most commonly for proof of what I deliver'd, to such tedious, such difficult, or such intricate Processes, as either You can scarce well make, unless You be already what I desire my Experiments should help to make You, a skilful Chymist; or else are as difficult to be well judg'd, as the truth they should discover is to be discern'd. I was also hopeful that the Easiness of divers things inviting you to make try∣al of them, and keeping You from being disappointed in Your Expectations, the success of Your first attempts would incourage You to make tryal also of more nice and difficult Experiments. And till You have try'd them, do me the right to think that I deal not unsincerely with You.

The Reasons of my having divers times recorded Expe∣riments which You may have formerly met with, and per∣chance ev'n in Printed Books, I have elsewhere deduc'd in a peculiar Discourse on that Subject: and therefore shall now only add, that by reason of my being as yet a stranger to the German Tongue, wherein the most and best Chy∣mical Books are said to be written, I may have set down

divers Chymical Experiments and Observations that are extant already in that Hermetical Language, (if I may so call it) without having had them from their Dutch Pub∣lishers, or so much as dream'd of their having been divulg'd by any man. I have likewise in my Preface to the Essays that you will meet with under the Title of Promiscuous Experiments, given You an account why I have not re∣frain'd from mentioning divers things which may seem very slight, because very obvious: And I have long had thoughts to inform You in an intire Discourse to be writ∣ten on purpose, why I think that ev'n the trivial, and therefore slighted, truths of Physiology ought not to be despis'd. And for my own part, I shall not scruple to confess to You, that I disdain not to take Notice ev'n of Ludicrous Experiments, and think that the Plays of Boys may sometimes deserve to be the Study of Philosophers: For as when we go a Hunting, though the flight of the Hare and the pursute of the Dogs be to us but sport and recreation, yet the Beasts themselves are extreamly ear∣nest, the one to save his threatn'd life by flight, and the other to overtake his desired Prey; so Nature acts very seriously in all the other things that we make sports with, and is in very good earnest, whether we Men be so or no.

Perhaps you will wonder, Pyrophilus, that in almost every one of the following Essays I should speak so doubt∣ingly, and use so often, Perhaps, It seems, 'Tis not improbable, and such other expressions as argue a diffidence of the truth of the Opinions I incline to, and that I should be so shy of laying down Principles, and sometimes of so much as venturing at Explications. But I must freely confess to you, Pyrophilus, that having met with many things of which I could give my self no one probable cause, and some things of which several Causes may be assign'd so differing, as not to agree in any thing unless in their being all of

them probable enough, I have often found such Difficul∣ties in searching into the Causes and Manner of things: and I am so sensible of my own Disability to surmount those Difficulties, that I dare speak confidently and posi∣tively of very few things, except of Matters of fact. And when I venture to deliver any thing by way of Opinion, I should, if it were not for meer shame, speak yet more diffi∣dently than I have been wont to do. 'Tis not that I at all condemn the Practice of those Inquisitive Wits that take upon them to explicate to us ev'n the abstrusest Phaeno∣mena of Nature: For I am so far from censuring them, that I admire them when their Endeavours succeed, and applaud them ev'n where they do but fairly attempt. But I think 'tis fit for a man to know his own Abilities and Weaknesses, and not to think himself oblig'd to imitate all that he thinks fit to praise. I know also that the way to get Reputation, is, to venture to explicate things, and promote Opinions: For by that course a Writer shall be sure to be applauded by one sort of men, and be mention'd by many others; whereas by the way of Writing to which I have condemn'd my self, I can hope for little bet∣ter among the more daring and less considerate sort of men, should you shew them these Papers, than to pass for a Drudge of greater Industry than Reason, and fit for little more than to collect Experiments for more rational and Philosophical heads to explicate and make use of. But I am content, provided Experimental Learning be ••eally promoted, to contribute ev'n in the least plausible Way to the Advancement of it, and had rather not only be an Underbuilder, but ev'n dig in the Quarries for Materials towards so useful a Structure, as a solid body of Natural Philosophy, than not do something towards the Erection of it. Nor have my thoughts been altogether idle and wanting to themselves, in framing Notions, and attempt∣ing to devise Hypotheses, which might avoid the deficien∣cies

observ'd in other mens Theories and Explications: but I have hitherto, though not always, yet not unfrequently, found that what pleas'd me for a while, as fairly comport∣ing with the Observations on which such Notions were grounded, was soon after disgrac'd by some further or new Experiment, which at the time of the framing of those No∣tions was unknown to me, or not consulted with. And indeed I have the less envy'd Many (for I say not All) of those Writers who have taken upon them to deliver the Causes of things, and explicate the Mysteries of Nature, since I have had opportunity to observe how many of their Doctrines, after having been for a while applauded and even admir'd, have afterwards been confuted by the dis∣covery of some new Phaenomenon in Nature, which was either unknown to such Writers, or not sufficiently consi∣der'd by them. For I have found it happen as well to many others (that have publisht their Opinions) as to me (who have been more private in my Guesses) in our Theo∣ries built on either too obvious or too few Experiments, what is wont to happen to the Falsifiers of Coyn: for as Counterfeit pieces of Money will endure some of them One Proof, as the Touch-stone, others Another, as Aqua fortis, some a third, as the Hammer or the Scales, but none of them will endure All proofs; so the Notions I mention (in which sort I fear too great a part of those hitherto ex∣tant may be compriz'd) may agree very fairly with this or that or the other Experiment, but being made too hastily, and without Consulting a competent number of them, 'tis to be fear'd that there may still after a while be found one or other, (if not many) their Inconsistency with which will betray and discredit them.

I have notwithstanding all this on some occasions adven∣tur'd to deliver my Opinion, not that I am very confident of being less subject to erre in those particulars than in any of the others wherein I have refrain'd from interposing any

Conjecture, but because I would manifest to You, that I scruple not to run the same venture with those incompara∣bly better Naturalists, that have thought it no disgrace in difficult matters rather to hazard the being sometimes mistaken, than not to afford Inquisitive Persons their best Assistance towards the Discovery of Truth.

And because, Pyrophilus, in the Reasons and Explica∣tions I offer of Natural Effects, I have not for the most part an immediate recourse to the Magnitude, Figure, and Motion of Atoms, or of the least Particles of Bodies, I hold it not unfit to give You here some account of this Practice, not so much for the sake of those few Passages in my Essays that may be concern'd in it, as for that of many Learned men, especially Physitians, whose useful Writings begin to be undervalu'd, and are in danger to be despis'd, by an Opinion taken up from the mis-understood Doctrine of some eminent Atomists, as if no speculations in Natural Philosophy could be rational, wherein any other causes of things are assign'd than Atoms and their Properties. I consider then, that generally speaking, to render a reason of an Effect or Phaenomenon, is to deduce it from somthing else in Nature more known than it self, and that conse∣quently there may be divers kinds of Degrees of Explica∣tion of the same thing. For although such Explications be the most satisfactory to the Understanding, wherein 'tis shewn how the effect is produc'd by the more primitive and Catholick Affection of Matter, namely, bulk, shape and motion, yet are not these Explications to be despis'd, wherein particular effects are deduc'd from the more ob∣vious and familiar Qualities or states of Bodies, such as Heat, Cold, Weight, Fluidity, Hardness, Fermentation, &c. Though these themselves do probably depend upon those three universal ones formerly nam'd. For in the search after Natural Causes, every new measure of Discovery does both instruct and gratifie the Understanding, though

I readily confess, that the nearer the discover'd Causes are to those that are highest in the scale or series of Causes, the more is the Intellect both gratify'd and instructed.

I think it therefore very fit and highly useful, that some speculative Wits well vers'd in Mathematical Principles and Mechanical Contrivances, should employ themselves in deducing the chiefest Modes or Qualities of Matter, such as are Heat, Cold, &c. and the States or conditions of it, (if we think fit to distinguish these from its Quali∣ties) as fluid, firm, brittle, flexible, and the like, from the above-mention'd most primitive and simple Affections thereof. And I think the Common-wealth of Learning exceedingly beholden to those Heroick Wits that do so much as plausibly perform something in this kind. But I think too, we are not to despise all those Accounts of particular Effects which are not immediately deduc'd from those primitive Affections of either Atoms or the insensible Particles of Matter, but from the familiar, though not so universal, Qualities of things, as cold, heat, weight, hard∣ness, and the like. And perhaps it would be none of the least advantages which would accrue to Naturalists from a satisfactory explication of such Qualities by the most primitive and simple ones, that it would much shorten the explication of particular Phaenomena: For though there be many things in Nature that may be readily enough made out by the Size, Motion, & Figure of the small Parts of Mat∣ter, yet there are many more that cannot be well explain'd without a great deal of Discourse, and divers successive Deductions of one thing from another, if the purpos'd effect must be deduc'd from such primary and Universal Causes; whereas if we be allow'd to take the Notions of Cold, Heat, and the like Qualities for granted, the expli∣cations and proofs may be much more compendiously made. He gives some Reason why Stones and Iron and all other heavy Bodies will swim in Quick-silver, except

Gold, which will sink in it, that teaches, that all those other Bodies are in specie (as they speak) or bulk for bulk, lighter than Quick-silver, whereas Gold is heavier. He, I say, may be allow'd to have render'd a Reason of the thing propos'd, that thus refers the Phaenomenon to that known Affection of almost all Bodies here below, which we call Gravity, though he do not deduce the Phaenome∣non from Atoms, nor give us the cause of Gravity, as in∣deed scarce any Philosopher has yet given us a satisfactory Account of it. So if it be demanded, why, if the sides of a blown Bladder be somewhat squeez'd betwixt ones hands, they will, upon the removal of that which com∣press'd them, fly out again, and restore the Bladder to its former figure and dimensions, it is not saying nothing to the purpose, to say that this happens from the spring of those Aerial Particles wherewith the Bladder is fill'd, though he that says this be not perhaps able to declare whence proceeds the Motion of Restitution, either in a Particle of compress'd Air, or any other bent spring.

And as for the Reasons of things assign'd by Physitians, they must be most of them despis'd, unless we will allow of such explications as deduce not things from Atoms or their Affections, but only either from secondary Qualities, or from the more particular Properties of Mixt Bodies. If a Physitian be ask'd why Rhubarb does commonly cure Loosenesses, he will probably tell you as a Reason, that Rhubarb is available in such Diseases, because it hath both a Laxative vertue, whereby it evacuates Choler, and such other bad humours as are wont in such cases to be the pec∣cant Matter, and an astringent Quality, whereby it after∣wards arrests the Flux: But if you further ask him the Reason why Rhubarb purges, and why it purges Choler more than any other humour, 'tis ten to one he will not be able to give you a satisfactory answer. And indeed, not only the manner whereby Purgative Medicines Work,

but those other Properties whereby some Bodies are Diu∣retick, others Sudorifick, others Sarcotick, &c. are not I fear so easie to be intelligibly made out as men imagine, and yet a skilful Physitian would justly think himself wrong'd, if the Reasons he renders of things in his own Profession were deny'd the Name of Reasons, because made without recourse to Atomical Principles. And in∣deed, there are oftentimes so many subordinate Causes between particular Effects and the most General Causes of things, that there is left a large field wherein to exercise Mens Industry and Reason, if they will but solidly enough deduce the Properties of things from more general and familiar Qualities, and also intermediate Causes (if I may so call them) from one another. And I am the more backward to despise such kind of Reasons, because I else∣where declare, that there are Some (for I do not say, Many) things, as particularly the Origine of Local Motion, of which ev'n by the Atomical Doctrine no Physical Cause can well be render'd; since either such things must be ascrib'd to God, who is indeed the true, but the supernatu∣ral Cause of them, or else it must be said, (as it was by the old Epicureans) that they did ever belong to Matter, which, considering that the Notion of Matter may be com∣pleat without them, is not to give a Physical efficient cause of the things in Question, but in effect to confess that they have no such Causes. But of this elsewhere more.

In the mean time, that you may not be drawn away to undervalue such Writers as I have been pleading for, nor think you ought to refrain from writing what occurs to you, though true and useful, unless you deduce it, or at least can do so, from the Epicurean Notions, I shall here briefly represent to you, (what perhaps you will not here∣after think a despicable suggestion) that there are two ve∣ry distinct Ends that Men may propound to themselves in studying Natural Philosophy. For some Men care only

to Know Nature, others desire to Command Her: or to express it otherwise, some there are who desire but to Please themselves by the Discovery of the Causes of the known Phaenomena, and others would be able to produce new ones, and bring Nature to be serviceable to their par∣ticular Ends, whether of Health, or Riches, or sensual De∣light. Now as I shall not deny but that the Atomical, the Cartesian, or some such Principles, are likely to afford the most of satisfaction to those speculative Wits that aim but at the knowledge of Causes; so I think that the other sort of men may very delightfully & successfully prosecute their ends, by collecting and making Variety of Experi∣ments and Observations, since thereby learning the Qua∣lities and Properties of those particular Bodies they desire to make use of, and observing the power that divers Chy∣mical Operations, and other ways of handling Matter, have of altering such Bodies, and varying their effects upon one another, they may by the help of Attention and Industry be able to do many Things, some of them very Strange, and more of them very Useful in humane life. When a Gunner or a Souldier employs Gun-powder, it is not necessary that he should consider, or so much as know, of what and of how many Ingredients (much less of what kind of Atoms) it is made, and the proportion and manner wherein they are mingled; but the Notice Experience gives him of the power of that admirable Concrete, as it is made up and brought to his hands, suffices to enable him to perform things with it, that nothing but their being common and unheeded can keep from being admir'd. The Physitian that has observ'd the Medicinal vertues of Trea∣cle, without knowing so much of the names, much less the Nature of each of the sixty and odd Ingredients whereof it is compounded, may cure many Patients with it. And though it must not be deny'd, that it is an advantage as well as a satisfaction, to know in general how the Qualities

of things are deducible from the primitive Affections of the smallest parts of Matter, yet whether we know that or no, if we know the Qualities of this or that Body they compose, and how 'tis dispos'd to work upon other Bodies, or be brought on by them, we may, without ascending to the Top in the series of Causes, perform things of great Moment, and such as without the diligent Examination of particular Bodies would, I fear, never have been found out à priori ev'n by the most profound Contemplators. We see that the Artificers that never dream'd of the Epi∣curean Philosophy, have accommodated Mankind with a Multitude of useful Inventions, And Paracelsus, who (besides that he seems none of the most piercing and spe∣culative Wits) sure had little recourse to Atomical Noti∣ons, if he ever so much as heard of them, was able to per∣form some things that were truly admirable, besides those he vainly boasted of; as may appear not only by what I elsewhere represent, but by what Oporinus himself (as se∣verely as he otherwise writes against his deserted Master) confesses he saw of the stupendous cures which Paracelsus wrought with his famous Laudanum, (whatever he made it of.) But we need not go far to find a noble Example to our present purpose, since we see that the bare making of tryals with the Load-stone, and Irons touch'd by it, though the Experimentors were ignorant (as some fear we yet are) of the true and first Causes of Magnetical Phaeno∣mena, have produc'd Inventions of greater use to Man∣kind, than were ever made by Leucippus, or Epicurus, or Aristotle, or Telesius, or Campanella, or perhaps any of the speculative Devisers of new Hypotheses, whole Contem∣plations aiming for the most part but at the solving, not the encreasing or applying, of the Phaenomena of Nature, it is no wonder they have been more ingenious than fruitful, and have Hitherto more delighted than otherwise bene∣fitted Mankind: I say Hitherto, because though Expe∣rience

warrants me so to speak now, yet I am not unwilling to think that Hereafter, and perhaps in no long time, when Physiological Theories shall be better establish'd, and built upon a more competent number of Particulars, the Deductions that may be made from them may free them from all Imputation of Barrenness. But of these things I otherwhere (though not as I remember in any of the fol∣lowing Essays) more fully discourse.

And therefore I shall now resume the Subject that occa∣sion'd this long Excursion, and add to what I said in ex∣cuse of my venturing sometimes to deliver something as my Opinion in difficult or controverted cases, that I must de∣clare to you, Pyrophilus, that as I desire not my Opinions should have more Weight with you than the Proofs brought to countenance them will give them, so you must not expect that I should think my self oblig'd to adhere to them any longer than those Considerations that first made me embrace them shall seem of greater Moment than any that I can meet with in opposition to them. For Aristotle spoke like a Philosopher, when to justifie his Dissent from his Master Plato, he said among other things, That for the sake of Truth, men (especially being Philosophers) ought to overthrow ev'n their own Tenents (〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉.* 1.1) And though for a man to change his opinions, without seeing more reason to forsake them than he had to assent to them, be a Censurable Levity and In∣constancy of mind; yet to adhere to whatever he once took for truth, though by Accession of more light he dis∣cover it to be erroneous, is but a proud Obstinacy very injurious to Truth, and very ill becoming the sense we ought to have of humane frailties. And it ought to be esteem'd much less disgraceful to quit an Error for a Truth, than to be guilty of the Vanity and Perverseness of believing a thing still, because we once believ'd it. And

certainly, till a Man is sure he is infallible, it is not fit for him to be unalterable.

You will easily discern, Pyrophilus, that I have purpose∣ly in the ensuing Essays refrain'd from swelling my Dis∣courses with solemn and elaborate Confutations of other mens Opinions, unless it be in some very few Cases, where I judg'd that they might prove great impediments to the Advancement of Experimental Learning; and even such Opinions I have been wary of medling with, unless I sup∣pos'd I could bring Experimental Objections against them. For 'tis none of my Design to engage my self with or a∣gainst any one Sect of Naturalists, but barely to invite you to embrace or refuse Opinions as they are consonant to Experiments, or clear Reasons deduced thence, or at least analogous thereunto, without thinking it yet seasonable to contend very earnestly for those other Opinions which seem not yet determinable by such Experiments or Rea∣sons. And indeed, to allude to our former Comparison, I would endeavour to destroy those curious but ground∣less structures that men have built up of Opinions alone, by the same way (and with as little Noise) by which such fantastical structures as those I mention'd to have seen at Leyden may be demolish'd. To destroy which 'twere need∣less to bring battering Engines, since nothing is requisite to that effect but an encrease of Light. And Experience has shown us, that divers very plausible and radicated Opini∣ons, such as that of the Unhabitableness of the Torrid Zone, of the Solidity of the Celestial part of the World, of the Blood's being convey'd from the Heart by the Veins (not the Arteries) to the outward parts of the body, are generally grown out of request, upon the appearing of those new Discoveries with which they are inconsistent, and would have been abandon'd by the Generality of Ju∣dicious Persons, though no man had made it his business purposely to write Confutations of them: so true is that

Vulgar saying, that Rectum est Index sui & Obliqui.

But when at any time, Pyrophilus, I have been induc'd to oppose others, as I have not deny'd my self the freedom that is requisite unto Loyalty to Truth, so I have endea∣vour'd to use that Moderation and Civility that is due to the persons of deserving Men. And therefore you shall find me not only in one Essay oppose an Author whom in another I applaude, but sometimes you may find me com∣mending a Writer in the very same Page, perhaps, where I am endeavouring to disprove his Opinions: For I love to speak of Persons with Civility, though of Things with Freedom. Nor do I think it reasonable, either that any mans Reputation should protect his Errors, or that the Truth should fare the worse for his sake that delivers it. And as for the (very much too common) Practice of ma∣ny, who write, as if they thought, railing at a mans Person, or wrangling about his Words, necessary to the Confuta∣tion of his Opinions; besides that I think such a quarrel∣some and injurious way of writing does very much mis∣become both a Philosopher and a Christian, methinks it is as unwise, as it is provoking. For if I civilly endeavour to reason a man out of his Opinions, I make my self but one work to do, namely, to convince his Understanding: but if in a bitter or exasperating way I oppose his Errors, I encrease the Difficulties I would surmount, and have as well his Affections against me as his Judgment: and it is very uneasie to make a Proselyte of him that is not only a Dissenter from us, but an Enemy to us. And that which makes me the more dislike the bitter way of disputing which I am reprehending, is, that I have often observ'd, that though one of the Disputants alone be at first in the fault, yet the other is most commonly drawn to share in the Guilt, though to contract it he must imitate his Adver∣sary. For as a mad Dog by biting others is wont to make those he bites run mad like himself, and do promiscuous

Mischief; so these so provoking Writers are wont to en∣rage those they offend, and infect them also with their own virulent distemper. But, Pyrophilus, when I 〈◊〉〈◊〉 of dealing respectfully with those I dissent from, I 〈◊〉〈◊〉 be understood of such as have well deserved of Expe••••¦mental Learning, or at least been candid and sober 〈◊〉〈◊〉 quirers after Truth. For, as I think that it would muc•• discourage any prudent Person from venturing to commu∣nicate what he thinks he knows to the World, to find that an Error proceeding from humane Weakness, or the Dark∣ness and Abstrusity of things, seldom escapes being dete∣cted without being made matter of disgrace or reproach to the Author: so on the other side, when vain Writers, to get themselves a name, have presum'd to obtrude upon the credulous World such things, under the Notion of Ex∣perimental Truths, or even great Mysteries, as neither themselves ever took the pains to make tryal of, nor re∣ceiv'd from any credible Persons that profess'd themselves to have try'd them; in such cases, I see not how we are oblig'd to treat Writers that took no pains to keep them∣selves from mistaking or deceiving, nay, that car'd not how they abuse us to win themselves a name, with the same respect that we owe to those, who though they have miss'd of the Truth, believ'd they had found it, and both intended to deliver It, and took some (though not prospe∣rous) pains that they might convey nothing else to us.

I fear it will be requisite, Pyrophilus, to tell you why in some of the following Essays you will meet with many Passages transcrib'd out of other Authors, and in some very few or none at all. And therefore to give you first a short Account of the Particular mention'd last, I must mind you, that 'twas most suitable both to my Humor and Design to deliver only those things wherewith my own Observati∣ons, or Tryals, or Thoughts, had furnish'd me, without troubling you with the Repetition of those things which

had been deliver'd by others already; those kind of Re∣petitions, unless they be made upon some such grounds as we shall presently mention, seeming to me to be as vainly as ambitiously affected by many Writers, and being deser∣vedly troublesome to Judicioas Readers, who can easily discern that they add much more to the bulk of Books than of Knowledge. But this notwithstanding, Pyrophilus, I thought my self oblig'd on some occasions, for your sake, to overcome my Natural Averseness to stuff any Writings of mine with Passages transcrib'd from those of others, partly for the Reasons elsewhere insisted on, and partly for divers others. As First, because some Par∣ticulars are of that Strangeness, and of that Moment, that they need and deserve to be verify'd by more than a single Attestation. Next, because according to the Greek Pro∣verb, 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, it is not properly to say over the same thing again, when the Observation, Experiment, or other Passage of an Author, is either illustrated or otherwise improv'd by the Repetition, or else apply'd to some pur∣pose differing from that to which the Author brought it: That being applicable to many a single Experiment or Ob∣servation which Seneca somewhere says,* 1.2 Nulla Res consum∣mata est dum incipit; And, Etiamsi omnia à Veteribus in∣venta sunt, hoc semper novum erit, Vsus, & Inventorum ab aliis Scientia & Dispositio. And thirdly, because as the Planets and other Stars have (according to Astrologers) in their great Synods or Conjunctions, much more powerful, and sometimes other Influences on the Air and some other sublunary Parts of the World, than are ascrib'd to one or two of them out of that Aspect; so divers Particulars, which whilst they lay single and scatter'd among the Wri∣tings of several Authors were inconsiderable, when they come to be laid together in order to the same Design, may oftentimes prove highly useful to Physiology in their Con∣junction, wherein one of them may serve to prove one part

or circumstance of an important Truth, and another to explicate another, and so all of them may conspire toge∣ther to verifie that Saying, Et quae non prosunt singula, mul∣ta juvant. It may then I hope suffice to justifie me on this occasion, that not appealing to other Writers as to Judges, but as to Witnesses, nor employing what I have found already publish'd by them barely as Ornaments to imbel∣lish my Writings, and much less as Oracles by their Autho∣rity to demonstrate my Opinions, but as Certificates to attest Matters of fact, I may hope that their Testimonies will as well be illustrated by mine, as mine by their's, and that all of them may contribute to your better Infor∣mation.

And if, Pyrophilus, you grant that upon these Conside∣rations I have not done amiss to apply to my purpose divers of those things which I found deliver'd pertinently to them by those Writers which I chanc'd to cast mine Eyes on, I suppose you will not think I need to make you an Apology for my having made most use of the Passages of those Writers which I suppose will be most difficult to be met with (such as are many Books of Navigations and other Voyages) and especially of French Books not yet translated into English or Latin. And I think I shall less need to make an Excuse for my having for the most part set down the Passages I recited in the Authors own Words, that being one of the readiest ways I know to satisfie the Reader, and avoid injuring the Writer. And indeed, I have met with abundance of Quotations wherein the Transcriber doth so mistake, or so mis-represent the cited Authors Meaning, sometimes out of Inadvertence, but sometimes too I fear out of Indulgence to his own Hypo∣thesis, that if ever I should be tempted to trouble the World with any of my thoughts, I would beseech my Readers, not to look upon any thing as my Opinion or Asser∣tion that is not deliver'd in the entire Series of my own

Words; lest a Transcriber should make me deliver those things resolutely and dogmatically, which I deliver but haesitantly and conjecturally; and lest I should seem to set down those things Positively as Processes for whose suc∣cess I undertake, which I record but by way of Nar∣rative.

For my so frequently mentioning what I have bor∣row'd from other Writers, or receiv'd from my friends, I expect to be excus'd by that of Pliny, Benignum est (ut arbitror) & plenum ingenui Pudoris, confiteri per quos pro∣feceris. Though I have seen divers Modern Writers that so boldly usurp the Observations and Experiments of others, that I might justly apply to them what the same Pliny annexes; Scito enim, conferentem Authores me depre∣hendisse à juratissimis & proximis Veteres transcriptos ad Verbum, neque nominatos &c. If other Writers should not prove more equitable (for I will not say more thank∣ful) than such as these, they would quickly discourage those whose aims are not very noble and sincere, from gra∣tifying the Publick with Inventions, whose Praise and Thanks would be usurp'd by such as will not name them. But perhaps they would be more just if they reflected on what our Author further adds, Obnoxii profectò animi & infelicis ingenii est, deprehendi in furto malle quam mutuum reddere, cum praesertim sors fiet ex Vsura.

And now I have said this concerning the Passages I have borrow'd from other Authors, it will not be improper to add something about those I have declin'd to borrow. For you may possibly marvel, that in divers of the Historical parts of my Writings I have omitted such Testimonies ei∣ther of Pliny, Solinus, Aristotle, Theophrastus, Aelian, or perchance some of the ancient Physitians themselves (who yet, as more conversant with things, are usually more cre∣dible) as seems very pertinent to my Discourse, and fit to prove what I design. But when I shall come to entertain

you about Natural History, I doubt not but to satisfie you with the Reasons I shall offer you of this Practice. In the mean time, I shall only tell you in short, that though I have a just respect for those Great Names I have men∣tion'd; yet the sense I have of the difficulties I have found to make and relate an Observation accurately and faith∣fully enough for a Naturalist to rely on; and the occa∣sions I have had of looking into divers matters of fact de∣liver'd in their Writings, with a bold and an impartial Curiosity; have made me conclude so many of those Tra∣ditions to be either certainly false, or not certainly true, that except what they deliver upon their own particular Knowledge, or with peculiar Circumstances that may recommend them to my belief, I am very shy of building any thing of moment upon foundations that I esteem so un∣sure, and much less upon the suspected Passages that Wecker, Paracelsus, Porta, &c. abound with. And therefore (though I well enough know how much I impoverish my Discourse by this Niceness) yet I do not think it fair to imploy that as an Argument to convince you that has not that operation upon me my self. And I the rather take notice of my forbearing to make use of the Historical Tra∣ditions and Chymical or Magical Secrets that I meet in the above-mention'd Authors, or any other makers of Colle∣ctions, unless the Narrative be (as I was saying) expresly enough deliver'd upon the Writer's Personal Knowledge, or that of some other credible Witness; not only because I would give you an account why several of my Writings are unfurnish'd with what most Readers look on as the richest Ornaments of other mens, but because if this wari∣ness could be introduc'd, t'would be the most effectual way of perswading men to write those kind of Tracts I would recommend, Physiological Essays. For he that will con∣fine himself so strictly, will scarce be often tempted on

Physical Subjects, to write either Systems or Volumns.

Another things, Pyrophilus, I must needs advertise you of in reference to the ensuing Discourses, which is, That be∣sides those Deficiencies in point of Ratiocination which are due to my personal Disabilities, I have purposely let pass some Few (and but very Few) Inferences which I dis∣cern'd well enough not to be cogent, because I was willing to acquaint you upon some particular Occasions with all the Experiments then occurring to me, which I thought might contribute to the Illustration of the Subject in hand, though each of them apart did not irrefragably, nor in∣deed so much as strongly infer the Conclusion in order to which they seem'd to have been mention'd as Premisses. And this Practice I made the less scruple of, because I was willing to exercise thereby your Reasoning Faculty, and try how far you would discern the Tendency of several things, all of them pertinent enough to the Subject in hand, but not all of them concluding to the main design in order whereunto they were alledg'd. And I supposed that the things by me mention'd, though not conclusive, being yet Experimental, the mention of them, which in a strictly Logical way of reasoning must have been forborn, might well make you amends for the Exercise to which I intended they should put your Reason.

There remains yet one thing, Pyrophilus, of which I sup∣pose you will expect I should give you an Account; and that is, why in the ensuing Essays I have mention'd divers Experiments which I have not plainly and circumstantial∣ly enough delivered. To satisfie you concerning which, I must represent to you, First, That though for your sake I have oftentimes, contrary to my Reason and Genius, de∣liver'd things, to make them more clear, in such a Multi∣tude of words, that I now seem even to my self to have in divers places been guilty of Verbosity; yet in some

other passages, treating of things which Use had render'd very familiar to me, I may have, to shun Prolixity, una∣wares slipt into the Contrary Extream. Secondly, There are some Mechanical Experiments wherein I have purpose∣ly omitted some manual Circumstances, because I was un∣willing to prejudice some ingenious Trades-men, who make either a Livelyhood, or at least a gain, by the sale of the productions of such Experiments. And I made the less scruple to conceal such Mechanical Circumstances, (if I may so call them) because they were not necessary to the Physiological Knowledge of the Experiments: in naming of which my intention was to teach you rather Philosophy than Trades. Thirdly, I mention'd some things but darkly, either because I receiv'd them upon Condition of secrecy, or because some ingenious persons that commu∣nicated them to me, or others to whom I imparted them, do yet make, and need to make, a pecuniary advantage of them. Fourthly, And some things that, either having been the fruits of my own Labours, or obtain'd in Ex∣change of such, are freely at my own disposal, I have not yet thought fit so plainly to reveal, not out of an envious design of having them bury'd with me, but that I may be always provided with some Rarity to barter with those Secretists that will not part with one Secret but in Ex∣change for another, and think nothing worth their de∣siring that is known already to above one or two Persons. And I think it very lawful to reserve always some con∣ceal'd Experiments by me, wherewith to obtain the secrets of others, which being thereby gained, the other (as being no longer necessary to the former end) may freely be com∣municated.

And think not, Pyrophilus, that the bare mention of an Experiment as having been performed, though the way of making it be conceal'd, is of no use, if the Relator of the

Experiment be a Person that may safely be credited: For it is something to be assur'd that such and such things have been really perform'd, and consequently are possible to be done, though we be not yet particularly acquainted with the means of performing them. And he tells you some∣thing, that tells you upon his own Knowledge, that in such or such Bodies, or Ways of operating on them, con∣siderable things of such or such a Nature are to be met with. And for my part, when I go a Hawking or Setting, I think my self beholden to him that assures me that in such a field there is a Covey of Partridges, though he does no more towards the giving me them. And it is obvious how much Europe is beholden to Columbus for the Detecti∣on of many Countries in America which were not dis∣cover'd by him, nor perhaps till long after his Death, be∣cause he first inform'd us Knowingly that there were un∣known Regions beyond that vast Ocean which severs the Old World from the New. But I begin to digress, and therefore shall proceed to tell you, That I am the less troubled at my Omission of the circumstantial parts of some Experiments, because I think it will be much for your Advantage to try them over again your self. And as I have taken care by the truth of the Experiments I have deliver'd to secure your success, in case you try them aright; so I cannot be very sorry that you should in some Particulars have a kind of Necessity laid on you to exer∣cise your own industry, and thereby encrease your Ex∣perience.

But besides all that has been said, Pyrophilus, I must free∣ly confess to you, that there is one thing particularly rela∣ting to your self, which has made me refrain from deliver∣ing in the ensuing Essays some of the chief Chymical pro∣cesses wherewith they might have been enrich'd. For not yet knowing with what seriousness you will addict

your self to promote experimental Philosophy, nor what use you will make of what has been unveiledly commu∣nicated to you, I was somewhat unwilling that some things which had cost me a great deal of pains should yet fall into any man's hands that scorns to purchase Knowledge with some pains, and I was desirous, in case you shall prove as industrious as I hope you will, to have something by me to encourage and cherish your industry, which may be more suitable to your improved Knowledge. For I must confess to you, that in reference to the Chymical processes extant in the following Discourses, I look upon most of them but as trifles, not only in comparison of those things which a knowing Chymist might have deliver'd on the same subjects, but even in regard of divers processes (not im∣pertinent to those discourses) wherewith I my self, (as little as I am a Pretender in these Matters) am not unac∣quainted: and perhaps I would have given to the follow∣ing Treatises the Title of Trifles, instead of that of Essays, if I had not been afraid of discouraging you thereby, and if the Chymical part of them had been the chief thing wherewith I intended to acquaint you in them. But if the reception you give to what we have already writt••n, prove such as may encourage us to proceed, we may p••r∣haps, if God be pleas'd to vouchsafe us Life and Oppor∣tunity, be invited to impart to you those more con••••••era∣ble Chymical Experiments, which either the Comm••ni∣cation of our friends or our own Labours have 〈◊〉〈◊〉 us. For it will be much in the power of the Enter••••••••∣ment which these Papers shall meet with, to make them either the Beginning of our Labours of this nature, or ••he End. And in the mean time, I think I may venture to tell you, that, as inconsiderable as I have confess'd div••rs of the Chymical Processes mention'd in these Essays to be, yet if ever you take the pains (as I hope you will) to 〈◊〉〈◊〉

Experimental Essays, and confine your self to take as little upon trust as I have done, you will perhaps be ready to believe, that sometimes a short Essay of this nature, not to say some one single Experiment, may have cost me more than a whole Treatise written on such a Subject, whereon to be able without Discredit to write Books, it is almost sufficient to have read many. And give me leave to add, that as in such kind of Composures, oftentimes the enabling himself to give a considerable Advertisement, or even Hint, may cost the Writer more than the making of several Experiments; so it may be also more beneficial to the Reader than the Knowledge of them. For we must not always measure the Considerableness of things by their most obvious and immediate usefulness, but by their fitness to make or contribute to the discovery of things highly useful. As, if it be true, what is reported by good Au∣thors of the hazel Wand, or Virgula divinatoria, though the hazel Tree be much less considerable in reference to its fruit, or immediate productions, than a Peach-Tree, an Orange-Tree, or even an Apple-Tree; yet may it be made much more valuable than any of them, because whereas they only present us with fruits, this may assist us to discover in latent Mines inestimable Treasures.

I had almost forgot to advertise you, Pyrophilus, That whereas I have not been so sollicitous as most Writers are wont to be, to swell the ensuing Essays with the Enume∣ration of the various Opinions and Arguments of Authors about the Subjects I treat of, or to adorn them with acute Sentences, fine Expressions, or other Embellishments bor∣row'd from eminent Writers; it has not been, because I utterly dislike the making use of those passages in Classick or other Authors, that may either give (among the Admirers of those Writers) some Authority to our thoughts, or very handsomely and Emphatically express

them. For I remember, I have known it reprehended by Learned Men in Epicurus, That though he writ very much himse••f, he would not vouchsafe in his Writings to quote those of other Men. And that I have not refrain'd from making use, now and th••n, of those Philological Orna∣ments of Discourse, when they readily occur'd to me, and appear'd neither impertinent nor prolix, may I hope suf∣fice to keep me from being suspected of the Vanity of thinking my self above other mens assistance. But the reasons of my so much declining to make use of other mens Authority, or Expressions, were chiefly these. First, That the Weakness of my Eyes has this long time kept me from reading almost any Books, save the Scripture, with some Critical Expositions of it, and here and there some Porti∣ons of the Writings of those that pretend to teach their Readers Experimental Matters: And the unfaithfulness of my Memory as to things of no great Moment, has made me forget almost all the little Philological and florid Learning I was formerly acquainted with. And really, Pyrophilus, as for the Books that treat of Natural Philoso∣phy, I am so sensible of the smalness of the Advantage which my Disabilities have suffer'd me to make of them, that instead of being ambitious to appear a great Reader, I could be very well content to be thought to have scarce look'd upon any other Book than that of Nature. And in the next place, Pyrophilus, though I ignore not that by this plain and unadorn'd way of Writing, I unkindly deny my Essays many Embellishments which I might give them, and which perhaps you will think they do abun∣dantly need; yet my frequent Distempers, Journeys, and other Avocations, not allowing me so much time as I desir'd, to entertain you on Philosophical subjects, I thought it more requisite to spend those confin'd hours in acquainting you with my own thoughts, such as they are, than with those of

other Men; unless (as I formerly intimated) I can some way or other more than barely recite what I recite of theirs. And you will easily pardon me the injury which for your sake I do my own Reputation by this naked way of writing, if you, as well as I, think those the profitablest Writers, or at least the kindest to their Perusers, who take not so much Care to appear Knowing Men themselves, as to make their Readers such.

Notes

• * 1.1

  Ethic. Nicom. lib. 1. cap. 6.
• * 1.2

  Quaesti∣on. Na∣tural. lib. 6. cap. 5. Epistola 64.