On the Vital Principle/Book 2/Chapter 12

by Aristotle

CHAPTER XII.

It must be admitted, for the senses in general, that each one is receptive of the perceptible forms of things without the matter, as wax takes the impress from a seal-ring, without the iron or gold of which the ring is made; —takes the device, that is, without the metal on which the device is inscribed. In like manner, the sense is impressed by each object having colour, or savour, or sound; not, however, after the appellation of the object but, according as it is of a certain quality, and in a given relation to the sense. It is the primal organ in which this faculty exists; and it is identical with the object perceived, although different from it in mode of being; for, otherwise, the percipient would be some kind of magnitude. But it cannot belong either to that percipient or to sensation to be magnitude, as they are rather a relation to, and a faculty for the perception of the qualities of each object. Thus, it is, from these reasons, made manifest why sentient impressions in excess destroy the sentient organs; for if the motion of the impression be stronger than that of the organ, then the relation which constitutes sensation is dissolved, as harmony and tone become discordant, when the chords are struck too forcibly.

But why do not plants feel, seeing that they also possess a living part, and are impressionable by tangible qualities? And that they are so impressionable is shewn in their being both cooled and heated; but the cause is that they have not that mediate faculty, nor any such principle as admits of their receiving only the forms of things; that along with forms they are affected by the matter also.

It may be questioned whether impressions can be made by odour upon what may be without smell, or by colour upon what may be without vision, and so for other qualities and senses. But if that which is smelt be odour, then odour, if it produce anything, must produce smell, and thus nothing without smell can be affected by odour, and the same holds good for the other senses; neither can beings which are sentient be affected, save in so far as they are sentient. All which is made evident in that neither light nor darkness, sound nor odour, can act upon bodies, although that which is present with them may, as air with thunder splits wood. But yet tangible and sapid qualities do act upon bodies; for, otherwise, by what could inanimate things be acted upon and changed? Shall it then be said that those other qualities also act upon bodies? But all bodies are not impressionable by odour and sound, and those which are so are indefinite and mobile, such as is the air; for the air gives out odour, as if it had been subject to impression. What then is smell but impression of some kind? But smelling is a sentient perception; and the air having been impressed by odour, becomes quickly sensible to us.

Notes

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Note 1, p. 125. It is the primal organ, &c.] Philoponus and Simplicius, according to some commentators, believed that the "mind" was the organ or principle here alluded to; but Saint Hilaire is disposed to regard it as "sensibility, irrespective of any thinking principle." Trendelenburg inquires, what means the term 'primal' quid hoc πρῶτον? He seems, however, to consider the mind as the special seat of the faculty in question—"quod primum dicitur, id tacite mentem spectari videtur, quæ propria est hujus facultatis sedes; et ea prima quidem, si ab intimo fonte proficiscaris." It may, however, with some confidence, be assumed that this primal organ points, suggestively, to the brain; for it evidently implies a central organ connected with each of the senses, and receptive of all sentient impressions. Thus, such an organ, while receptive of form, may well be said to be identical with the object; and yet, seeing how opposed are the manifestations of the sensibility to the properties of matter, not be so, in an absolute sense. The organ, like the brain, in fact, being perceptive of forms and properties through the senses, is identified, pro tanto, with objects; although it cannot but differ from them absolutely, in mode of being, that is in essence.

Note 2, p. 126. But why do not plants feel, &c.] The answer to this question, by assigning to the organ a definite locality and function, seems to lend support to the explanation offered in the foregoing note. The passage in the original τὸ μὴ ἔχειν μεσότητα is rendered too freely, perhaps, in this version, as mediate faculty; but the French "qualité moyenne" is to the same purport. The Latin is, "neque id medium, tanquam mensuram et modum habent, quo sensus quasi judicant." It may be that as Aristotle had refused, so to say, sensibility to the brain, he found himself constrained, in order to explain the function of the senses and their power of recalling images, to adopt a central organ, to be as well the source of sensibility as the sensorium or store-house, for the mind and memory. He had been led, in fact, to regard the brain as insentient, because of its not imparting sensation when touched, and as subsidiary to the respiration for tempering the internal heat, because of its apparent coldness. All this was the settled conviction of this great man; Democritus, however, seems to have perceived that the brain is either the organ or the seat of sensibility, although the opinion was not generally admitted. Plato agreed with physiologists in making the seat of the senses to be the liver and neighbourhood of the heart, but he differed from Aristotle in believing the brain to be continuous with the spinal chord, and to be the source of the intellectual faculties. He held the brain, in fact, to be the seat if not the source of the higher faculties, while he assigned the appetites and coarser passions to the viscera. Hippocrates^[1], who lived some years before him, assigns to the brain the guardianship of the mind, and makes it to be not only the first percipient of all the changes of the seasons, but also the source and seat of all the more deadly and complicated maladies.

Note 3, p. 126. It may be questioned, &c.] The argument, in these passages, is to account for the changes which are constantly going on in bodies, and for which that age could assign no adequate cause; but still it was perceived that tangible and sapid qualities (hot and cold, wet and dry, acid, saline, astringent, and others) must be the agents principally concerned in their production. Thus, although neither light nor darkness, sound nor odour, can act upon bodies, yet something present with them may, and this seems to point, suggestively, to those imponderable and invisible forces (heat, magnetism, electricity, &c.), for which, as yet, even "no plausible theory has been adopted."

Note 4, p. 126. But all bodies are not impressionable, &c.] These passages are very obscure; but their purport seems to be, that odour and sound can act only upon such bodies as, like the air and water, are neither limited nor stationary—are made to be the carriers, as it were, of delicate emanations and vibrations to sentient organs. Thus, it is added, the air, having been impressed by odour, readily gives it out, and, then, through the smell, becomes perceptible to the sentient being. But neither odour nor sound, as such, can in aught contribute to the changes to which all inert bodies are subject; and the actions of sound and odour, therefore, seem to be limited to sentient, that is, living properties. This may be to us a truism, but it must be recollected that even to Aristotle the olfactory passages were but imperfectly known; that the opinions upon the Atmosphere were hypothetical; and that the processes by which changes are wrought in inert matter were still to be detected.

1. Epistola, T. iii. 824; T. i. 614.