Aristotle (De Anima, I. 1) makes in the first place the general remark that it appears as if the soul must, on the one hand, be regarded in its freedom as independent and as separable from the body, since in thinking it is independent; and, on the other hand, since in the emotions it appears to be united with the body and not separate, it must also be looked on as being inseparable from it; for the emotions show themselves as materialized Notions (λόγοι ἔνυλοι), as material modes of what is spiritual. With this a twofold method of considering the soul, also known to Aristotle, comes into play, namely the purely rational or logical view, on the one hand, and, on the other hand, the physical or physiological; these we still see practised side by side. According to the one view, anger, for instance, is looked on as an eager desire for retaliation or the like; according to the other view it is the surging upward of the heart-blood and the warm element in man. The former is the rational, the latter the material view of anger; just as one man may define a house as a shelter against wind, rain, and other destructive agencies, while another defines it as consisting of wood and stone; that is to say, the former gives the determination and the form, or the purpose of the thing, while the latter specifies the material it is made of, and its necessary conditions.
Aristotle characterizes the nature of the soul more closely (De Anima, II. 1) by referring to the three moments of existence: “First there is matter (ὕλη), which is in itself no individual thing; secondly, the form and the universal (μορφὴ καὶ εἶδος), which give a thing individuality; thirdly, the result produced by both, in which matter is potentiality and form is energy (ἐντελέχεια);” matter thus does not exist as matter, but only implicitly. “The soul is substance, as being the form of the physical organic body which is possessed potentially of life; but its substance is energy (ἐντελέχεια), the energy of a body such as has been described” (endowed with life). “This energy appears in twofold form: either as knowledge (ἐπιστήμη) or as active observation (τὸ θεωρεῖν). But it is evident that here it is to be regarded as the former of these. For the soul is present with us both when we sleep and when we wake; waking corresponds with active observation, and sleep with possession and passivity. But knowledge is in origination prior to all else. The soul is thus the first energy of a physical but organic body.” It is in respect of this that Aristotle gives to the soul the definition of being the entelechy (supra, pp. 143, 144).
In the same chapter Aristotle comes to the question of the mutual relation of body and soul. “For this reason” (because soul is form) “we must no more ask if soul and body are one than we ask if wax and its form are one, or, in general, if matter and its forms are one. For though unity and Being are used in various senses. Being is essentially energy.” Were we, namely, to pronounce body and soul one in the same way that a house, which consists of a number of parts, or as a thing and its properties, or the subject and predicate, and so on, are called one, where both are regarded as things, materialism results. An identity such as this is an altogether abstract, and therefore a superficial and empty determination, and a term which it is a mistake to employ, for form and material do not rank equally as regards Being; identity truly worthy of the name is to be apprehended as nothing else than energy such as has been described. The only question that now arises is whether activity and the organ it employs are one; and our idea is to answer in the affirmative. The more definite explanation of this relation is to be found in the following; “The soul is substance, but only according to the Notion (κατὰ τὸν λόγον); but that is the substantial form (τὸ τί ἦν εἶναι)[96] for such and such a body. For suppose that an instrument, such as an axe, were a natural body, this form, this axehood, would be its substance, and this its form would be its soul, for if this were to be taken away from it, it would no longer be an axe, the name only would remain. But soul is not the substantial form and Notion of such a body as an axe, but of a body which has within itself the principle of movement and of rest.” The axe has not the principle of its form in itself, it does not make itself an axe, nor does its form, its Notion, in itself constitute its substance, as its activity is not through itself. “If, for instance, the eye were in itself a living thing, vision would be its soul, for vision is the reality which expresses the Notion of the eye. But the eye, as such, is only the material instrument of vision, for if vision were lost, the eye would be an eye only in name, like an eye of stone or a painted eye.” Thus to the question, What is the substance of the eye? Aristotle answers: Are the nerves, humours, tissues, its substance? On the contrary, sight itself is its substance, these material substances are only an empty name. “As this is the case in the part, so it also holds good of the body as a whole. The potentiality of life is not in any such thing as has lost its soul, but in that which still possesses it. The seed or the fruit is such and such a body potentially. Like hewing and seeing,” in the axe and the eye, “waking” in general “is activity; but the corporeal is only potentiality. But as the” living “eye is both vision and the eyeball” (the two being connected as actuality and potentiality), “so also are soul and body the living animal, the two are not to be separated. But it is not yet clear whether the soul is the activity of the body in the same way as the steersman is of the ship.” That the active form is the true substance, while matter is so only potentially, is a true speculative Notion.
As settling the question asked in the above-mentioned metaphor, we may quote what Aristotle says later (De Anima, II. 4): “As the principle of motion and as end (οὗ ἕνεκα), and as substance of living bodies, the soul is the cause. For substance is to all objects the cause of their existence, but life is the existence of the living, and its cause and principle is the soul; and further, its energy is the existing Notion of what has potential existence. The soul is cause also as end,” that is, as self-determining universality, “for nature, like thought, acts for the sake of an object, which object is its end, but in living beings this is soul. All the parts of the body are thus the organs of the soul, and hence exist for its sake.” In like manner Aristotle shows that the soul is the cause of motion.
Aristotle (De Anima, II. 2, 3) further states that the soul is to be determined in three ways, namely as nutrient or vegetable, as sensitive, and as intelligent, corresponding with plant life, animal life and human life. The nutrient soul, when it is alone, belongs to plants; when it is at the same time capable of sense-perception, it is the animal soul; and when at once nutrient, sensitive and intelligent, it is the mind of man. Man has thus three natures united in himself; a thought which is also expressed in modern Natural Philosophy by saying that a man is also both an animal and a plant, and which is directed against the division and separation of the differences in these forms. That difference has also been revived in recent times in the observation of the organic, and it is highly important to keep these sides separate. The only question (and it is Aristotle who raises it) is how far these, as parts, are separable. As to what concerns more nearly the relation of the three souls, as they may be termed (though they are incorrectly thus distinguished), Aristotle says of them, with perfect truth, that we need look for no one soul in which all these are found, and which in a definite and simple form is conformable with any one of them. This is a profound observation, by means of which truly speculative thought marks itself out from the thought which is merely logical and formal. Similarly among figures only the triangle and the other definite figures, like the square, the parallelogram, &c., are truly anything; for what is common to them, the universal figure, is an empty thing of thought, a mere abstraction. On the other hand, the triangle is the first, the truly universal figure, which appears also in the square, &c., as the figure which can be led back to the simplest determination. Therefore, on the one hand, the triangle stands alongside of the square, pentagon, &c., as a particular figure, but—and this is Aristotle’s main contention—it is the truly universal figure. In the same way the soul must not be sought for as an abstraction, for in the animate being the nutritive and the sensitive soul are included in the intelligent, but only as its object or its potentiality; similarly, the nutritive soul, which constitutes the nature of plants, is also present in the sensitive soul, but likewise only as being implicit in it, or as the universal. Or the lower soul inheres only in the higher, as a predicate in a subject: and this mere ideal is not to be ranked very high, as is indeed the case in formal thought; that which is for itself is, on the contrary, the never-ceasing return into itself, to which actuality belongs. We can determine these expressions even more particularly. For if we speak of soul and body, we term the corporeal the objective and the soul the subjective; and the misfortune of nature is just this, that it is objective, that is, it is the Notion only implicitly, and not explicitly. In the natural there is, no doubt, a certain activity, but again this whole sphere is only the objective, the implicit element in one higher. As, moreover, the implicit in its sphere appears as a reality for the development of the Idea, it has two sides; the universal is already itself an actual, as, for example, the vegetative soul. Aristotle’s meaning is therefore this: an empty universal is that which does not itself exist, or is not itself species. All that is universal is in fact real, as particular, individual, existing for another. But that universal is real, in that by itself, without further change, it constitutes its first species, and when further developed it belongs, not to this, but to a higher stage. These are the general determinations which are of the greatest importance, and which, if developed, would lead to all true views of the organic, &c., since they give a correct general representation of the principle of realization.
α. The nutritive or vegetative soul is therefore, according to Aristotle (De Anima, II. 4), to be conceived as the first, which is energy, the general Notion of the soul itself, just as it is, without further determination; or, as we should say, plant life is the Notion of the organic. What Aristotle goes on to say of nourishment, for instance, whether the like is nourished by the like, or by the opposite, is of little importance. It may, however, be mentioned that Aristotle (De Anima, II. 12) says of the vegetative soul that it is related only to matter, and that only after a material manner, as when we eat and drink, but that it cannot take up into itself the forms of sensible things: we, too, ourselves in practical matters are related as particular individuals to a material existence here and now, in which our own material existence comes into activity.
β. There is more to interest us in Aristotle’s determination of sense-perception (De Anima, II. 5), as to which I shall make some further quotations. Sense-perception is in general a potentiality (we should say a receptivity), but this potentiality is also activity; it is therefore not to be conceived as mere passivity. Passivity and activity pertain to one and the same, or passivity has two senses. “On the one hand a passivity is the destruction of one state by its opposite; on the other hand, it is a preservation of what is merely potential by means of what is actual.” The one case occurs in the acquisition of knowledge, which is a passivity in so far as a change takes place from one condition (ἕξις) into an opposite condition; but there is another passivity, in which something only potentially posited is maintained, therefore knowledge is knowing in an active sense (supra, p. 182). From this Aristotle concludes: “There is one change which is privative; and another which acts on the nature and the permanent energy (ἕξις). The first change in the subject of perception (αἰσθητικοῦ) is caused by that which produces the perception; but, once produced, the perception is possessed as knowledge (επιστήμη).” Because that which produces the change is different from the result, perception is passivity; but it is just as much spontaneity, “and sense-perception, like knowledge (θεωρεῖν), has to do with this aspect of activity. But the difference is, that what causes the perception is external. The cause of this is that perceptive activity is directed on the particular, while knowledge has as its object the universal; but the universal is, to a certain extent, in the soul itself as its substance. Everyone can therefore think when he will,” and for this very reason thought is free, “but perception does not depend on him, having the necessary condition that the object perceived be present.” The influence from without, as a passivity, comes therefore first; but there follows the activity of making this passive content one’s own. This is doubtless the correct point from which to view perception, whatever be the manner of further development preferred, subjective idealism, or any other way. For it is a matter of perfect indifference whether we find ourselves subjectively or objectively determined; in both there is contained the moment of passivity, by which the perception comes to pass. The monad of Leibnitz appears, it is true, to be an idea opposed to this, since every monad, every point of my finger, as atom or individual, is an entire universe, the whole of which develops in itself without reference to other monads. Here seems to be asserted the highest idealistic freedom, but it is of no avail to imagine that all in me develops out of me; for we must always recollect that what is thus developed in me is passive, and not free. With this moment of passivity Aristotle does not fall short of idealism; sensation is always in one aspect passive. That is, however, a false idealism which thinks that the passivity and spontaneity of the mind depend on whether the determination given is from within or from without, as if there were freedom in sense-perception, whereas it is itself a sphere of limitation. It is one thing when the matter—whether it be sensation, light, colour, seeing or hearing—is apprehended from the Idea, for it is then shown that it comes to pass from the self-determination of the Idea. But it is different when, in so far as I exist as an individual subject, the Idea exists in me as this particular individual; there we have the standpoint of finitude established, and therefore of passivity. Thus there need be no standing on ceremony with sense-perception, nor can a system of idealism be based on the theory that nothing comes to us from without: as Fichte’s theory about himself was, that when he put on his coat, he constituted it in part by drawing it on, or even by looking at it. The individual element in sensation is the sphere of the individuality of consciousness; it is present therein in the form of one thing as much as of another, and its individuality consists in this fact, that other things exist for it. Aristotle continues: “Speaking generally, the difference is that potentiality is twofold; as we say a boy may become a general, and a grown man may also become so,” for the latter has the effective power. “This is the nature of the faculty of sense-perception (αἰσθητικόν); it is in potentiality what the object of sense (αἰσθητόν) is in actuality. Sense-perception is therefore passive, in so far as it does not resemble its object, but after the impression has been made it becomes similar to its object, and is identified with it.” The reaction of sense-perception consists therefore in this active receiving into itself of that which is perceived; but this is simply activity in passivity, the spontaneity which abrogates the receptivity in sense-perception. Sense-perception, as made like to itself, has, while appearing to be brought to pass by means of an influence working on it, brought to pass the identity of itself and its object. If then subjective idealism declares that there are no external things, that they are but a determination of our self, this must be admitted in respect to pure sense-perception, since sense-perception is a subjective existence or state in me, which yet, however, is not for that reason freedom.
In speaking of sense-perception, Aristotle (De Anima, II. 12) makes use of his celebrated simile, which has so often occasioned misapprehension, because it has been understood quite incorrectly. His words are: “Sense-perception is the receiving of sensible forms without matter, as wax receives only the impress of the golden signet ring, not the gold itself, but merely its form.” For the form is the object as universal; and theoretically we are in the position, not of the individual and sensuous, but of the universal. The case is different with us in our practical relations, where the influence working upon us pre-supposes in return the contact of the material, for which reason, as Aristotle asserts, plants do not perceive (supra, p. 186). On the other hand, in receiving form, the material is lost sight of; for the receiving of form indicates no positive relation to the matter, which is no longer something offering resistance. If, therefore, sense-perceptions are termed in general sensuous impressions, we, in matter-of-fact fashion, do not get beyond this crude way of putting it; and in making the transition to soul, we take refuge behind popular conceptions, which are partly ill-defined Notions, and partly not Notions at all. Thus it is said that all sense-perceptions are impressed on the soul by external things, just as the matter of the signet ring works on the matter of the wax; and then we hear it alleged that this is Aristotle’s philosophy. It is the same with most other philosophers; if they give any sort of illustration that appeals to the senses, everyone can understand it, and everyone takes the content of the comparison in its full extent: as if all that is contained in this sensuous relationship should also hold good of the spiritual. No great importance is therefore to be attached to this conception, as it is only an illustration, professing to show by a side comparison that the passive element in sense-perception is in its passivity for pure form only; this form alone is taken up into the percipient subject, and finds a place in the soul. It does not, however, remain in the same relation to it as that in which the form stands to the wax, nor is it as in chemistry where one element is permeated by another as regards its matter. The chief circumstance, therefore, and that which constitutes the difference between this illustration and the condition of the soul is altogether overlooked. That is to say, the wax does not, indeed, take in the form, for the impression remains on it as external figure and contour, without being a form of its real Being; if it were to become such, it would cease to be wax; therefore, because in the illustration there is lacking this reception of form into the Being, no thought is given to it. The soul, on the contrary, assimilates this form into its own substance, and for the very reason, that the soul is in itself, to a certain extent, the sum of all that is perceived by the senses (infra, p. 198): as it was said above (p. 183), if the axe had its form in the determination of substance, this form would be the soul of the axe. The illustration of the wax has reference to nothing but the fact that only the form comes to the soul; and has nothing to do with the form being external to the wax and remaining so, or with the soul having, like wax, no independent form. The soul is by no means said to be passive wax and to receive its determinations from without; but Aristotle, as we shall soon see (p. 194), really says that the spirit repels matter from itself, and maintains itself against it, having relation only to form. In sense-perception the soul is certainly passive, but the manner in which it receives is not like that of the wax, being just as truly activity of the soul; for after the perceptive faculty has received the impression, it abrogates the passivity, and remains thenceforth free from it (supra, p. 187). The soul therefore changes the form of the external body into its own, and is identical with an abstract quality such as this, for the sole reason that it itself is this universal form.
This description of sense-perception Aristotle explains more fully in what follows (De Anima, III. 2), and expatiates upon this unity and its contrasts, in the course of which explanation there appear many clear and far-reaching glimpses into the Nature of consciousness. “The bodily organ of each sense-perception receives the object perceived without matter. Hence, when the object of sense is removed, the perceptions and the images which represent them remain in the organs. In the act of sense-perception the object perceived is no doubt identical with the subject that perceives, but they do not exist[97] as the same; for instance, sound and the hearing are the same when in active exercise, but that which has hearing does not always hear, and that which has sound is not always sounding. When that which is the potentiality of hearing comes into exercise, and likewise that which is the potentiality of sound, hearing and sound, being in full activity, coincide,” they do not remain separate energies. “If then movement and action, as well as passivity, have a place in the object on which activity is exercised (ἐν τῷ ποιουμένῳ), it follows necessarily that the energy of hearing and sound is contained in that which potentially is hearing, for the energy of the active and moving is in the passive. As therefore activity and passivity are manifested in the subject which receives the effect, and not in the object which produces it (ποιοῦντι), the energy both of the object and of the faculty of sense-perception is in the faculty itself. For hearing and sounding there are two words, for seeing only one; seeing is the activity of the person who sees, but the activity of the colour is without name. Since the energy of that which is perceived and that which perceives is one energy, and the aspect they present is alone different, the so-called sounding and hearing must cease simultaneously.” There is a body which sounds and a subject which hears; they are twofold in the aspect they present, but hearing, taken by itself, is intrinsically an activity of both. In like manner, when I have by sense the perception of redness and hardness, my perception is itself red and hard: that is, I find myself determined in that way, even though reflection says that outside of me there is a red, hard thing, and that it and my finger are two; but they are also one, my eye is red and the thing. It is upon this difference and this identity that everything depends; and Aristotle demonstrates this in the most emphatic way, and holds firmly to his point. The later distinction of subjective and objective is the reflection of consciousness; sense-perception is simply the abrogation of this separation, it is that form of identity which abstracts from subjectivity and objectivity. What is simple, the soul proper or the I, is in sense-perception unity in difference. “Further, every sense-perception is in its organ, and distinguishes everything that is perceived, like black and white, and so on. It is thus not possible for separate perceptions, white and sweet, to be distinguished as separate indifferent moments, for both must be present (δῆλα) to one subject. This one subject must therefore determine one thing to be different from another. This, as distinguished, can also not be in a different place or time, for it must be undivided and in undivided time. But it is impossible that one and the same thing should be affected by contrary movements, in so far as it is undivided and in undivided time. If sweetness affects sense-perception in one way, and bitterness in the contrary way, and whiteness in yet another way, the power of judging is numerically not discrete nor divisible, but according to the Notion (τῷ εἶναι)[98] it is distinguished. That which is the same and indivisible thus possesses in potentiality opposite qualities; but with its true existence (τῷ εἶναι) that cannot be the case, for in its activity it is separable, and cannot at the same time be both white and black. Sense-perception and thinking are like that which some term a point, which, in so far as it is one, is inseparable, and in so far as it is two, is separable. So far as it is undivided, the judging faculty is one and acts in a single point of time, but so far as it is divided” (not one) “it employs the same sign twice simultaneously. So far as it employs two, it by limitation distinguishes two, and separates them as having separate origin; but so far as it is one, it judges by one act in one single point of time” (supra, p. 172). For as the point in time, which resembles the point in space, contains future and past, and thus is something different and at the same time one and the same, since it is in one and the same respect separation and union; sense-perception is also one and at the same time separation, separated and not separated, seeing that the faculty of perception has before it in one unity the distinct sense-perception, which by this means receives for the first time a determinate content. Another example is that of number; one and two are different, and, at the same time, even in two one is used and posited as one.
γ. From sense-perception Aristotle passes on to thought, and becomes here really speculative. “Thinking,” he says (De Anima, III. 4) “is not passive (ἀπαθές), but receptive of the form, and is in potentiality similar to it. Therefore the understanding (νοῦς), because it thinks all things, is free from all admixture (ἀμιγής), in order that it may overcome (κρατῇ), as Anaxagoras says, that is, in order that it may acquire knowledge; for, coming forth in its energy (παρεμφαινόμενον), it holds back what is alien to it, and fortifies itself against it (ἀντιφράττει). Therefore the nature of the understanding is none other than this potentiality.” But potentiality itself is here not matter; that is to say, the understanding has no matter, for potentiality pertains to its very substance. For thinking is really the not being implicit; and on account of its purity its reality is not the being-for-another, but its potentiality is itself a being-for-self. A thing is real because it is this determinate thing; the opposite determination, its potentiality to be, for instance, smoke, ashes, and so on, is not posited in it. In the corporeal, therefore, matter, as potentiality, and external form, as reality, are opposed to one another; but the soul is, in contrast with this, universal potentiality itself, without matter, because its essence is energy. “Understanding, then, in the soul, as that which possesses consciousness, is nothing in reality before it thinks;” it is absolute activity, but exists only when it is active. “It is therefore not incorporated with the body. For what should it be like, warm or cold? Or should it be an organ? But it is none of these. That it is, however, different from the faculty of sense-perception is clear. For sense-perception cannot perceive after a violent perception; for instance, it cannot smell nor see after experiencing strong smells or colours. But the understanding, after it has thought something which can only be thought with difficulty, will not have more but less difficulty in thinking of something that is easier. For there is no sense-perception independent of the body, but the understanding is separable from it. When it has then become something individual, like him who is really possessed of a faculty of knowing (and this happens when he can energize through himself), it then is also in a certain degree according to potentiality, but yet not so in the same manner as it was before learning and finding.” (Cf. supra, pp. 182, 187.)