XII
An examination of the question where the ruling principle is to be considered to reside; wherein also is a discussion of tears and laughter, and a physiological speculation as to the interrelation of matter, nature, and mind.41
Let there be an end, then, of all the vain and conjectural discussion of those who confine the intelligible energy to certain bodily organs; of whom some lay it down that the ruling principle is in the heart, while others say that the mind resides in the brain, strengthening such opinions by some plausible superficialities. For he who ascribes the principal authority to the heart makes its local position evidence of his argument (because it seems that it somehow occupies the middle position in the body),42 on the ground that the motion of the will is easily distributed from the centre to the whole body, and so proceeds to operation; and he makes the troublesome and passionate disposition of man a testimony for his argument, because such affections seem to move this part sympathetically. Those, on the other hand, who consecrate the brain to reasoning, say that the head has been built by nature as a kind of citadel of the whole body, and that in it the mind dwells like a king, with a bodyguard of senses surrounding it like messengers and shield-bearers. And these find a sign of their opinion in the fact that the reasoning of those who have suffered some injury to the membrane of the brain is abnormally distorted, and that those whose heads are heavy with intoxication ignore what is seemly.
Each of those who uphold these views puts forward some reasons of a more physical character on behalf of his opinion concerning the ruling principle. One declares that the motion which proceeds from the understanding is in some way akin to the nature of fire, because fire and the understanding are alike in perpetual motion; and since heat is allowed to have its source in the region of the heart, he says on this ground that the motion of mind is compounded with the mobility of heat, and asserts that the heart, in which heat is enclosed, is the receptacle of the intelligent nature. The other declares that the cerebral membrane (for so they call the tissue that surrounds the brain) is as it were a foundation or root of all the senses, and hereby makes good his own argument, on the ground that the intellectual energy cannot have its seat save in that part where the ear, connected with it, comes into concussion with the sounds that fall upon it, and the sight (which naturally belongs to the hollow of the place where the eyes are situated) makes its internal representation by means of the images that fall upon the pupils, while the qualities of scents are discerned in it by being drawn in through the nose, and the sense of taste is tried by the test of the cerebral membrane, which sends down from itself, by the vertebrae of the neck, sensitive nerve-processes to the isthmoidal passage, and unites them with the muscles there.
I admit it to be true that the intellectual part of the soul is often disturbed by prevalence of passions; and that the reason is blunted by some bodily accident so as to hinder its natural operation; and that the heart is a sort of source of the fiery element in the body, and is moved in correspondence with the impulses of passion; and moreover, in addition to this, I do not reject (as I hear very much the same account from those who spend their time on anatomical researches) the statement that the cerebral membrane (according to the theory of those who take such a physiological view), enfolding in itself the brain, and steeped in the vapours that issue from it, forms a foundation for the senses; yet I do not hold this for a proof that the incorporeal nature is bounded by any limits of place.
Certainly we are aware that mental aberrations do not arise from heaviness of head alone, but skilled physicians declare that our intellect is also weakened by the membranes that underlie the sides being affected by disease, when they call the disease frenzy, since the name given to those membranes is φρένες. And the sensation resulting from sorrow is mistakenly supposed to arise at the heart; for while it is not the heart, but the entrance of the belly that is pained, people ignorantly refer the affection to the heart. Those, however, who have carefully studied the affections in question give some such account as follows:—by a compression and closing of the pores, which naturally takes place over the whole body in a condition of grief, everything that meets a hindrance in its passage is driven to the cavities in the interior of the body, and hence also (as the respiratory organs too are pressed by what surrounds them), the drawing of breath often becomes more violent under the influence of nature endeavouring to widen what has been contracted, so as to open out the compressed passages; and such breathing we consider a symptom of grief and call it a groan or a shriek. That, moreover, which appears to oppress the region of the heart is a painful affection, not of the heart, but of the entrance of the stomach, and occurs from the same cause (I mean, that of the compression of the pores), as the vessel that contains the bile, contracting, pours that bitter and pungent juice upon the entrance of the stomach; and a proof of this is that the complexion of those in grief becomes sallow and jaundiced, as the bile pours its own juice into the veins by reason of excessive pressure.
Furthermore, the opposite affection, that, I
