Note 1, p. 109. And there seems to be an analogy, &c.] Aristotle in thus making Touch superior to, and more influential than any other sense, (for it is the most perfect, he observes, of man's senses, although with respect to some others he is inferior to many animals,) is supported by Cuvier, who says, "that Touch is the most important of all the senses, and that its several degrees of perfection exercise a surprising influence over the nature of different animals; and that of all the vertebrata man has the most perfect Touch." It is difficult to attach a sense to the term hard or soft applied to flesh, which, by anatomical description, corresponds with the muscular substance of the body; but man is said to have softer flesh than any animal, and on this account, through the delicacy of his sense of Touch, to be of all creatures the most intelligent. It is presumable that Aristotle was led to suppose, from this sense being spread, so to say, like the muscular substance, over the surface of the body, that its organ lies somewhere in or beneath the flesh, and thus to have concluded that a relative hardness or density of that substance, by impeding tangible impressions, may be the cause of, or concomitant with dulness of the faculties. The nervous system was then unknown, and Aristotle, so fond of analogies, might readily suppose that the Touch had, like other senses, its appointed organism; and, if there were such an organ, that it is extended over the body, and thus must be in or beneath the flesh. The Taste, as being a modification of Touch, was said to be more delicate in man than animals.
Note 2, p. 110. There is a close analogy.] A similar observation is made in the following chapter, and, besides bringing sentient perceptions under some general law, it was, probably, intended to shew that colour, sound, and odour, although inappreciable by our senses, may still be present. It shews, in fact, that our senses, being limited in their capacity of perception, are not to be relied upon when impressions are very greatly in excess or proportionally faint.
Note 3, p. 111. The smell is perceptive.] "That fishes smell," Aristotle observes, "is shewn in their being taken by baits which have the particular odour, foul or grateful, to which they are attached." But modern science has, of course, determined both the seat and the structure of the olfactory organ in fishes; and shewn "how it is protected from the violent and incessant action of the currents of water required for respiration." Sanguineous creatures are all such as have red blood, and insanguineous, those which, in place of red blood, have a pale bluish fluid circulating in their veins. These last include "insects, molluscs, crustacea, and creatures with more than four feet."
Note 4, p. 111. And hence the difficulty of determining, &c.] If the site and structure of the olfactory sense, in the lower forms of life, are still somewhat conjectural, it may well be supposed that the smell in non-breathing animals was, in that age, although seen to be a fact, inexplicable. But yet, although anatomy could not then determine the seat of the sense, it might have been conjectured that, as such creatures are obviously affected by odours, there must be some other inlet for them than that through which impression is made upon animals; and the detection of this mode of perception, would have been another instance of homologous physiology. Aristotle, following Plato, placed the seat of the smell and other senses in the neighbourhood of the heart; but "the organ was said to be located, suitably, between the eyes."
Note 5, p. 112. The olfactory organ in man, appears to differ, &c.] The analogy is obviously faulty, as it seems to imply that the olfactory, like the respiratory organs, are furnished with a cover, by the raising of which odours gain access to the sense; or rather, owing to the intricacy of the parts and imperfect anatomical knowledge, the epiglottis has been associated with the velum and posterior fauces. It could answer no purpose, then, to inquire, as some have, what animals have an operculum for the smell, of that kind? or what mean those veins and pores? As although the operculum, that is, the epiglottis, was known to be protective of the larynx and, therefore, the respiratory organs, the relations of the larynx with the parts associated with it had not been made out; and the veins and pores refer, probably, to the bronchi and vessels within the chest.
Note 6, p. 112. In fine, odour is derived, &c.] Aristotle here differs from Plato, who held that odorous particles are in a state rather of fluidity; and Cuvier says, that "the organ of smell is moistened with abundant viscosity, which arrests the odorous particles contained in air or water; as fishes are sensible of odours. But odour, being regarded as exhalation, was assumed to be of fiery nature and, therefore, like the element, dry, and this required, for the conformity of the hypothesis of like upon like, that the organ of the sense, when in potentiality, should be also dry, and so, in due relation to odour.
Prelude to Chapter X.
This theory of taste and savour is adopted substantively by modern physiology. Cuvier says that "Taste is only a more delicate kind of Touch;" and Müller considers fluid essential to its manifestations. There are three conditions essential to Taste, he observes, the specific nerve, the excitation of that nerve through savour, and the solution of the savour in the moisture of the sapid organ; for sapid matter to be tasted, must either be moistened, or else be solvable in the tongue's moisture. All which implies that, if an object is very arid, or if the organs of Taste are incapable of supplying moisture, the percipient will be sensible, not of sapid but, of tangible qualities only, such as hot and cold, hard and soft.
Chapter X.
Chapter X.
The sapid object is a kind of tangible object, and this is the reason why it does not require, in order to be perceived, any other medium than the body, for the Touch requires no other. The body in which is savour, is the gustable body, and the matter of savour is in fluid, and fluid is something tangible. Thus, were we in the water, and were any thing sweet cast into the water, we should be sensible of the sweetness, not through the water as a medium but, from its having been mixed with the water as with a potable fluid. Colour, however, is not thus made visible from having been mixed with anything, nor is it made visible by emanations; and as the medium, in the case of colours, plays no part and colour is the visible, so is savour the gustable. No object, however, without humidity can impart the sense of savour; and, therefore, every sapid object contains humidity, in an active or a potential state, as does salt; for salt is readily moistened and liquefied by contact with the tongue.
Now, vision is perceptive of the visible and the invisible (for darkness, although invisible, is still judged of by vision), and a very bright light (which is also invisible, although in a manner different from darkness), and so hearing is equally perceptive of sound and silence, of which that is audible and this inaudible, as well as a very loud sound, just as vision is of a very bright light; for as a very low sound is, in a certain sense, inaudible, so is a very loud and crashing sound. On the other hand, the term invisible, used absolutely, is analogous to the term impossible upon other subjects, and which may be significant of something generated without parts or with parts ill formed for their office, as an animal without feet, or a fruit without a kernel. So, too, the taste in its turn is perceptive both of what is sapid and insapid; and the insapid implies whatever has a faint or nauseous savour, or a savour altogether perversive of taste. The potable and the impotable seem alike to be the origin of taste, for they both are sapid; but then the first has a nauseous savour, and is perversive of taste, while the last is genial to the sense; the potable is common, besides, to the touch and taste. Since whatever is sapid is humid, it follows that the organ of taste may neither be humid really, nor yet be incapable of becoming humid; for the taste suffers impression by the sapid body, in so far as it is sapid. It is, therefore, necessary that the sentient organ, if not moist, should, for its function, be capable of becoming so: and, as proof of this, the tongue, when very dry or very moist, is not sensible of sapid impressions—as in the former instance, it is a tangible rather than a sapid impression which is made by a fluid when first tasted; and when very moist, it is sensible only of the fluid already present, just as it happens when, after tasting something pungent, we proceed to taste a different fluid. It is thus that all savours appear to the sick to be bitter, because the tongue, with which they taste, is charged with a moisture having that savour.
Kinds of savour are, like shades of colour, simple when in broad contrast—as the sweet and bitter with their sequences, of the former the oily and of the latter the brackish; and intermediate to these are the pungent, rough, astringent, and sour, which seem to include almost all the varieties of savour.
In fine, the sapid sense, when in potentiality, is such as is the sapid object; and the sapid object, when in reality, is productive, in the sense, of its own savour.
Notes Layout 2 Note 1, p. 114. Colour, however, is not thus made visible.] The opinion here objected to originated with Democritus. Aristotle held it to be absurd to suppose that colour and vision could be a process of emanation from the eyes; for colour produces sensation, he observes, not by emanation but, by contact, and so it is better, at once, to admit that vision is produced by the action of the medium. There are, it is said, seven distinctions of colour and as many of savour; and in another work seven vowels, seven pleiads, and seven chords.
Note 2, p. 114. No object, however, which is without humidity.] This is little more than a repetition of what had been said concerning sapid substances. Aristotle seems to have adopted a theory, derived from mechanics, for explaining the solubility of objects--Whence comes it, he asks, that an earth is both melted and moistened by fluid (καὶ τήκεται καὶ τέγγεται) while soda (τὸ δὲ νίτρον) is melted but not moistened? The answer is, because there are pores throughout the soda which cause its parts to be, at once, separated by the fluid; while the pores in the earth are in alternate rows, so that the influence of the fluid, in whatever way it may gain access, cannot but be different.
Note 3, p. 114. As vision is perceptive, &c.] The argument here is interrupted and obscured by parenthetical explanations; but the purport is, that the senses are the sole judges of sentient impressions through all their degrees of intensity, and that, as sensibility is a mean, they cannot discriminate such as are far above or below the allotted medial standard. There is a seeming discrepance, however, in employing the term invisible as analogous to impossible on other subjects, as vision is not altogether lost in any darkness; but a creature without feet could not continue its existence, nor a fruit without the kernel continue its species.
Note 4, p. 115. The impotable as well as the potable, &c.] The impotable implies, of course, whatever is neither moist nor capable of becoming moist, and every such substance must, necessarily, pain—be very disagreeable to, that is—and pervert the Taste. All these passages, however, while proving that moisture is required for savour, point to a want of knowledge of the salivary and mucous glands which were yet to be discovered. But over and above the due conditions of moisture, there was still required the knowledge of the nervous system to account for the many perversions of Taste which are manifested, both in sick and well; and manifested, at times, without any apparent cause. It will occur to many, besides, how differently the Taste is affected by the same substance, as sugar for instance, in different persons, and even, at times, in the same person.
Note 5, p. 116. Kinds of savour are like shades of colour, &c.] There must ever be difficulty in fixing upon terms for savours or other sentient qualities, and still greater difficulty in settling what are the exact equivalents for such terms in another, and that not a cognate tongue; for although some savours, as bitter and sweet, may be supposed to have an universal acceptation, there are others which, being far less definite, are subject to variation, according to climate and race. So that, with the exception of bitter and sweet, it can hardly be pretended that the other terms, as oily, pungent, rough, astringent, &c., are perfect representatives of those in the text.
Note 6, p. 116. In fine the sapid sense, &c.] This passage does but repeat what has been already insisted upon, that the sense, in potentiality, that is, when inactive, is identical with that which is to act upon it; but that, having been acted upon, it is brought into the state of reality, and then becomes perceptive of the qualities of the excitant.
Prelude to Chapter XI.
Commentators have differed widely in their interpretation of Aristotle's meaning in the opening passage upon the Touch. But it may, with some confidence, be assumed that, from being unacquainted with the nervous system, and observing the wide-spread and varying delicacy of the sense, he was led to suppose that it might either be diffused, so to speak, as several organs, over the body, or be somehow identified with or included in the flesh which covers the body. The flesh is the muscular substance, and as it envelopes, so to say, the body, it was probably supposed to be the seat or cause of the sense, as every part is sensible to Touch; and the analogue of flesh is the colourless substance of the Insanguinea insects, &c And there is a close analogy between the two substances, “as the muscles of the highest class of animals, during their development pass through the soft, colourless, homogeneous and gelatinous condition of the Invertebrata, before assuming the red colour." As the Touch, besides, was regarded as the first in order of the senses and characteristic of animals, so the flesh was said to be the origin of all other parts of animal bodies, bone and skin, sinews, veins, hair and nails; and this hypothesis may have confirmed the opinion that it is either the sense or the seat of the sense of Touch.
CHAPTER XI.
CHAPTER XI.
The same reasoning holds good for the tangible quality as for the Touch; for if the Touch be not a single but a manifold sense, it follows that tangible qualities must be manifold also. Now, it is difficult to determine whether the Touch is a manifold or a single sense, and difficult also to say what the organ may be which is percipient of tangible qualities; that is, whether or not it is the flesh, and that which, in other creatures, is analogous to flesh; but yet the flesh is only the medium, and the essential organ, therefore, must be something different from flesh, and situated internally.
Each sense seems to be perceptive of only one contrary, as Sight of white and black, Hearing of acute and grave, and Taste of bitter and sweet; but several contraries belong to the sense of Touch, as hot and cold, wet and dry, hard and soft, with others. There is, it is true, a kind of solution for this difficulty, in that the other senses also admit of several contraries; as in the voice there are not only the acute and grave but also the strong and weak, the rough and smooth, with yet other contrasts; and there are many and varied shades of colour. Still it is not clear what that subjacent something is, which is to the tangible impression what the Hearing is to Sound.
Is then the sentient organ placed or not within the flesh, or is it the flesh itself which is immediately perceptive? It does not appear that any indication can be obtained upon this point from sensation being simultaneous with the tangible impression; for, situated as we are, were any one to extend a membranelike substance over his flesh, the party would be equally sensible when touched, and sensible at the moment of contact; and yet, clearly, the sentient organ cannot be in that membrane. It may be, however, that if the membrane were a congenital part of the body, sensation would pass through it more rapidly. Thus, this part of the body appears to be disposed towards us as air would be, had air been diffused around us; for it would seem to us as though by some one sense we perceive sound, colour, and odour, and as though sight, hearing, and smell, are one and the same sense. But now, as the motions emanating from external objects are distinguishable by the medium through which they are conveyed, the sentient organs alluded to must manifestly be different also. With respect to the Touch, however, this is still obscure, for it is impossible that a living body should be constituted out of air or water, as it must have some solidity; and there remains only this conclusion, that it must be a mixture of earth, and such other particles as have affinity with flesh, and the analogue of flesh. Thus, the body has, of necessity, been adapted for being the medium for the tangible sense, through which the several tangible impressions are to be conveyed; and that the impressions are manifold is shewn in the tongue being perceptive of tangible as well as sapid qualities. We are sensible, in fact, by this organ of all tangible as well as sapid qualities; and were the rest of the flesh, like the tongue, sensible of savour, then "Taste" and "Touch" would seem to be one and the same sense; but now we perceive, since they are not convertible, that they must be distinct senses.
It may be a question whether, as all bodies have depth, that is the third magnitude, any two bodies, which have between them another body, can be in contact; for neither the humid nor the liquid is incorporeal, as each must, of necessity, be water or hold water; and thus, it follows that, as the extreme parts of bodies in the water are not dry, the water, with which their extremities are covered, must be interposed between them. If this be true, then it is impossible that one body, when in the water, should be in immediate contact with another; and this holds good for bodies in the air; for the air is in the same relation to bodies in air which water is to bodies in water; but owing to our being in the air, the fact as readily escapes us, as it does aquatic animals, from their being in water, that water is in immediate contact with water. It may then be asked whether there is but one mode of impression for all the senses, or whether it is different for different senses, seeing that taste and touch are acted upon by contact, and the other senses from a distance? But yet this is a seeming difference only, for we perceive the hard and the soft, as we do the odorous, the sonorous, and the visible, through media; with this difference, that the former impressions are made by objects close to, and the latter by objects at a distance from us. On which account, as we perceive all things through a medium, the medium, in the case of bodies close to us, escapes our attention; but if, as we have already said, we could be sensible of all tangible impressions through a membraneous substance, without our being conscious of their having been so transmitted, we should then be situated as we now are, when in water or air; for so situated, we seem to touch bodies directly, and to have no impression from them through a medium.
But tangible differ from visible and sonorous impressions, in that the latter are perceived by the medium acting in some way upon us, while the former are perceived, not by, but together with, the medium, like a man who is struck through his shield; —for it is not the shield which, having been struck, strikes him, but the shield and he are simultaneously struck together. To use a general expression, the flesh and the tongue seem to be in the same relation to the touch which air and water are to sight, hearing, and smell; —are disposed towards that organ, that is, as each of those elements is to each of those senses. When the sentient organ itself is touched, no sensation can there or then be produced, any more than a white object can be seen when placed immediately over the surface of the eye; and thus it is evident that the part perceptive of tangible impressions must be within. Thus, it should be with the touch, as with the other senses; and if objects, when placed upon an organ, are not perceived, but, when placed upon the flesh, they are perceived, we must conclude that the flesh is only the medium for tangible impressions.
The distinctions of the body, as body, are tangible distinctions, and by these I mean distinctions such as distinguish the elements, as hot, cold, dry and moist, upon which we have heretofore spoken in our treatise upon the Elements. The organ which perceives those distinctions is that of Touch; and the part in which resides, primarily, the so-called sense of Touch is, in potentiality, what tangible impressions are in reality; for all sensation is a kind of impression. So that whatever, by its agency, makes something else to be as itself, can do so only from that something being already, as itself, in potentiality. Hence, we are not sensible of hot and cold, hard and soft, when manifested in the same degree as in ourselves, but perceive them only when in excess, as if the sensibility were some kind of mean between the contraries of sentient impressions, and able, as such, to judge of sentient perceptions. The mean, in fact, is critical—for it is either of the extremes in its relation to the other; and as that which is to perceive white and black may be neither one nor the other actually, and yet both potentially, so it is with the other senses, and with touch, which may be neither hot nor cold.
As vision was said to be, in some sense, perceptive of the visible and the invisible, and the other senses equally of their opposites, so Touch may be said to be perceptive of the tangible and the intangible; and by intangible is meant as well what differs but slightly from what is tangible, as air for instance, as what is in such excess as to be destructive of all sensation.
We have thus then spoken, although but superficially, upon each of the senses.
Notes Layout 2 Note 1, p. 118. Each sense seems to be perceptive, &c.] This passage seems to imply that all sentient impressions may, in a strict sense, be tangible impressions. Aristotle, in another treatise, observes that sentient bodies are bodies sensible of tangible impressions, and that tangible impressions only have contraries, which, in kind, are specific and causative. And, "thus, neither whiteness and blackness, sweetness and bitterness, or any other contraries save those alluded to, can form elementary distinctions." All which implies, perhaps, that the Touch is either the origin of or coeval with animal existence; and that the other senses are but for the higher forms of being. The properties, besides, which are attributed, so to say, to the Touch are, in contradistinction to those of the organs of relation, mainly concerned in the changes continually going on in inert bodies; and this consideration may have, in part, contributed to the speculative opinion just quoted.
Note 2, p. 120. It may be a question whether as all bodies, &c.] This is an argument to prove that, as there cannot be absolute contact of bodies in water, so neither can there be in air; and thus that the flesh can be only the medium for tangible impressions—that there must ever be air interposed, that is, between the object and the surface of the body. It may seem now to be supererogatory, but, as the atmosphere had not then been experimentally investigated, crude and contrary opinions, as might be supposed, were entertained concerning it, and its manifold relations. The term "third magnitude" is derived from, or associated with the Pythagorean doctrine of number—as of magnitude, continuous length is referrible to one, breadth to two, and depth to three; and, thus, depth is the "third degree" of or relation to magnitude.
Note 3, p. 122. But tangible differ from visible, &c.] "It will be evident that whatever may, in these passages, be erroneous, is traceable to the flesh being regarded as the sense or the medium for the sense of Touch, as, in either case, the Touch, differing from every other sense, would, from what has been maintained, require two media. There seems to be something like forgetfulness in withdrawing, so to say, the medium in the example given of tangible impression, and supposing that the man and his shield can be simultaneously transfixed.
Note 4, p. 122. The different states of the body as a body, &c.] As the Touch was regarded as a primal or elementary sense, so the qualities, of which it is perceptive, (as hot and cold, dry and moist, &c.) were also regarded as elementary qualities; and distinguished from visual or sonorous impressions, by being necessary to animal existence. It is uncertain whether the work "upon the Elements" here alluded to was a distinct work, or a chapter in one of the treatises which have been cited; but the question is of little consequence, and foreign, besides, to the purpose of these notes.
Note 5, p. 123. The mean, in fact, is critical, &c.] This is a transfer, so to say, of moral to physical relations. "Whatever is continuous and divisible comprehends," Aristotle says, "the three terms, more, less, and equal, which all bear a relation either to the thing itself or to ourselves; for the equal is a given mean between excess and deficiency. Now, the mean implies that which is equidistant from either of the extremes, and it is one and the same in all material conditions; but the mean, in relation to us, implies a state in which there is neither excess nor deficiency." Thus, temperance nourishes and preserves the body, while excess or deficiency of food and drink tends to destroy it. Moderate exercise increases, while immoderate or insufficient exercise impairs the strength; and so for other conditions which are readily adducible.
Note 6, p. 123. As vision was said to be in some sense, &c.] The passage is obscure, but it seems to repeat a former observation, that, as the senses can judge of sentient properties only in their mediate state, the terms invisible and intangible are, strictly speaking, incorrect and inapplicable." The air, moving in currents, was said to be wind;" and, when at rest, it was supposed, like all else, when either in excess or deficiency, to be withdrawn from sentient perception.
Prelude to Chap. XII.
Having treated of each of the senses, Aristotle here proceeds to consider the source of sensation, the sensibility, that is, which is typified as plastic wax, from its capability of receiving the form of an object without its matter. This comparison is indeed a happy one; and it has been often employed by writers in modern times, and "among others by Bossuet." The chapter shews that for perception there must be a due relation between impression and sense, and that plants are insentient because they have no faculty for the reception of the forms of objects; and it concludes by shewing that the agency of some properties, as light, sound, &c., is confined to the sentient organs.
CHAPTER XII.
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 Layout 2 Notes Layout 2 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