An entire body of philosophy according to the principles of the famous Renate Des Cartes in three books, (I) the institution ... (II) the history of nature ... (III) a dissertation of the want of sense and knowledge in brute animals ... / written originally in Latin by the learned Anthony Le Grand ; now carefully translated from the last corrections, alterations, and large additions of the author, never yet published ... by Richard Blome.

CHAP. XI. That the Senses are an Effect of the Nerves; and that the Soul of Man only feels, for asmuch as it resides in the Brain.

I. How the Nerves ••onduce to the forming of the Senses; and how the Soul rules in the Brain. THo' it sufficiently appears from the fore∣going Chapter what Sense is, and how by the Ministry of the Nerves External Objects are communicated to us; yet it remains still for us to enquire, how the Nerves perform this; and why the Senses rather have their residence in the Brain, than in any other part of the Body. Both which, tho' they be different Points, I shall comprehend in this Chapter.

II. Three things are to be con∣sider'd in the Nerves. In the first place, we are to take notice, that the Nerves are Vessels fitted for the containing and conveying of Spirits, proceeding from the Pith within the Brain. Secondly, That there are 3 things to be considered of in the Nerves; First, The thin Skins wherein they are wrapt or cover'd, which proceeding from the Coats or Membrans that encompass the Brain, are dispersed throughout the Body into small branches like Pipes. Secondly, That their Inward Substance, which is divided into very fine filaments or Strings, do reach from the Brain, whence they take their rise, to the utmost Parts of the Body, with which these Ner∣vous filaments are interwoven. Lastly, The Ani∣mal Spirits, which like a Wind, or most subtil Air, rushing through these little Pipes, do move the Muscles, by way of Inflation or blowing of them up. It remains now that we say something, how those Strings or Capillaments which are within the Tubes of the Nerves, are subservient to Sensa∣tion.

III. How the Nerves are subservient to Sensa∣tion. Which will not be difficult to understand, if we suppose that these Capillaments do reach to the Extremities of all the Members, that are capable of any sense; so that if any part of those Mem∣bers, to which the Nerve is fastned, be never so little stirr'd, at the same Moment that part of the Brain from whence that Nerve proceeds, must be moved also. Which we may Experience in a stretched-out Rope, whereof if the one end be touched, the other must be moved at the same time. So that all the diversity of Impressions that are made upon the Brain, do arise from the Nerves, which carry the various Qualities of the Objects along with them.

IV. How the Body is excited from Ex∣ternal Ob∣jects, to move it self. We must therefore imagine, that those small Filaments that are derived from the inmost Recesses of the Brain, and constitute the Pith or Marrow of the Nerves, are so disposed in all those Parts that are the Organ of any Sense, as that they may be most easily and readily moved by the Objects of those Senses. And that whensoever those Filaments are never so little moved, they draw those parts of the Brain, whence they pro∣ceed, and at the same time open the Orifices of some Pores, that are in the inward Surface of the Brain, through which the Animal Spirits in the Ventricles of the Brain, begin immediately to di∣rect their course, and through them rush into the Nerves and Muscles that are the Instruments of those Motions, that are altogether like them that are excited in us, when our Senses are so and so affected.

V. The Soul of Man hath its Resi∣dence in the Brain. As to the second Particular, viz. That the Soul of Man doth feel, that is, sensibly perceive all things; not as it is in the Organs of the External Senses, but only inasmuch as it is in the Brain, which is the Center and Rise of all the Nerves, this is evident from Examples and Reason. For when we see Light, or hear a Sound, we must not imagine that the Soul exerts this Act of Sensation in the Eye or the Ear; but that it perceives these things in its own place or seat, by means of the Nerves that reach from those parts to the Brain. For if the Soul did see in the Eye, and hear in the Ear, since both these Organs are double, there must needs follow a double perception of one and the same Object, at the same time: And since the contrary is most evident, it follows, that the Soul feels only in that part of the Body where the 2 Impressions, which proceed from one Object, through the double Organs of the Senses, are united again into one, before they affect the Soul.

VI. Proved from the Experi∣ment of Vapours and Wound••. This may be confirmed from manifold Experi∣ments: For we find by daily Experience, that the Vapours which ascend from our Stomach to the Brain, and being condens'd there, do obstruct the passages through which the Animal Spirits have their course, do deprive a Man of the Power of Sensation. We find also that Diseases, which affect the Brain, or Wounds that are inflicted in it, do destroy the Senses; as is manifest in those that are struck with the Apoplexy. In like manner in Fren∣zies, wherein the Imagination is spoiled, Remedies are applied to the Head, which would be very foolishly done, if the Senses had their Residence in any other part of the Body. Hence it is that they who are seiz'd with the Apoplexy, are immediately deprived of all their Senses, so as not to be sensible, tho' they be slash'd with Knives or prick'd with Pins. And for the same Reason it is, that Persons that have their Attention fix'd upon any thing, do not take notice of things that are done in their presence; because the Soul residing in the Brain, is otherwise taken up, so as not to take notice o•• the things that ore offer'd unto it.

VII. Another Instance taken from those, who are troubled with the Vertigo, or Turning of the Brain. But no mor•• convincing Argument can be al∣ledg'd to prove, that the Soul doth sensibly per∣ceive in the midst of the Brain, than that which is taken from the Vertigo, in which all External Objects seem to move round; whereas indeed there is no such motion, neither in the Objects them∣selves, nor in the Outward Senses; but it proceeds only from the Spirits in the Brain, being so moved, which affecting the Soul, it rashly attri∣butes the said Circular motion to the Objects that are about it.

VIII. The same thing con∣firmed from the Pain that persons think they Feel in the part they have lost. Moreover, they that are earnestly busie about Serious Matters, or are wearied with long Study, are sensible of a Pain in their Head; which I my self, after a little Study, frequently Experience: Which would not be so, if the Soul had not its Residence in the Brain, and did imagine and feel there. Besides, it sometimes happens that Pain seems to be felt in that part which is cut off from the Body; according to what DES CARTES tells us of a Girl that had her Arm cut off, who afterwards complain'd of a pain she felt in her Fingers. Which could not proceed from any other Cause, but because the Nerves, which came from the Brain to the Hand, upon the cutting off of her Arm, reacht no further than her Elbow, where being affected after the same manner, as they used to be when her Hand was yet pained, made her suppose, that she felt the same pain she formerly felt in her Fingers. For such is the Na∣ture of our Body, that no part of it can be moved by another, which is a little distant from it; but that it must be moved in like manner by those Parts that come between. As is manifest in a Rope, the End whereof may as well be pull'd or hal'd by that Part which is nearest to the midst, as by the other End opposite to it.

IX. When we have lean∣ed long upon our Elbow, we find a Pain in our Little Finger. In like manner it sometimes happens, that after having leaned long upon our Elbow, we are sen∣sible of a Numness in our Little Finger; because the Nerve which ends in that Finger, being too much prest upon, doth affect the Organ of the Common Sense, as if the Finger it self were so prest. For we are wont to affix the Sense of Pain to that part, which is wont to be moved by the Objects, and wherein the stretched Fibres of the Nerves are terminated.

X. In what part of the Brain the Soul hath its Seat. Wherefore it is necessary, that the Soul have its Residence in that part of the Brain, to which the Filaments of our Nerves do reach; to the end that it may take care for the Security of all the parts of the Body, and may have timely notice of, and provide for any Casualties that happen to the Body. For tho' all the Changes of the Fibres, consist only in some certain motions, which com∣monly do only gradually differ; yet must the Soul consider them as Changes that are Essentially di∣stinct, and that forasmuch as they cause so great an Alteration in the Body to which it is joyned. For the Motion, by Example, that causeth Pain, tho' it frequently differ but little from that Motion, the effect whereof is Titillation: Yet, because by the former some of the Fibres of the Body may be pluck'd out of their places, or broken, whereas the latter is an Argument of the firm and entire Constitution of our Body, so it is that the Soul ap∣prehends these 2 motions, as being essentially distin∣guish'd. As to what particular part of the Brain the Soul hath chosen for its Residence, shall be declared in the next Part of these Institu∣tions.

XI. The Impres∣sion from the Object is only made upon the Soul. But you'l say, It cannot be denied, but that we see with our Eyes, and feel pain in our Feet: Why then should we say, that the Function of Sense is only performed in the Brain, and not rather in these outward Organs of our Bodies?

True it is, that the Impression that is made by the Object, is begun in the Organs of the outward Senses; but it is not perfected or compleated there. We see with our Eyes, forasmuch as the Impressions of Lig ht and Colour are made upon them: But all this while the Action of the Soul, whereby this Impression is perceived, is exerted in the more par∣ticular and chief Residence of the Soul; as will appear more plainly in what follows.