Lecture 5 — The soul’s powers in general

Of the soul’s powers already spoken of, all are present in some, only some are present in others, and only one in yet others. By the powers of the soul, we mean the vegetative, the sensitive, the appetitive, the locomotive and the intellectual.

In plants there is only the vegetative; in other living things, this and the sensitive power; but if the sensitive power is present, so must the appetitive be present, for appetite is desire, anger, and will. Now, all animals have one sense, touch; and where sensation is found there is both joy and sorrow, both the agreeable and the disagreeable. What has these has desire, for this appetite is for the delightful.

Further, all have a sense of food, for touch is a sense of food. For all living beings are nourished by things dry and wet or hot and cold; and the sense of touch is of these. But they are nourished by the other sense-objects accidentally; for sound, color, and smell contribute nothing to nutrition; and as for savor, it is something belonging to the objects of touch. Hunger and thirst being desires, hunger for the hot and dry, and thirst for the cold and wet, savor is, as it were, the delectable in these. We must settle these questions later; for the present let us only say that animals endowed with touch have appetite also. The case of imagination is not clear and must be examined later. Some animals, again, have local motion; some have intellect and understanding—such as men and if there is something else of this sort or even more excellent.

It is, therefore, clear that the account of soul must be one in the same way as that of figure: for just as there is no figure apart from the triangle and those that derive from it, so there is no soul apart from the aforesaid. There will be, however, in the case of figures, an account common to all figures yet proper to none. Likewise with these souls just mentioned. Hence it is absurd to seek a common account in this matter (or in any other) which will be the proper account of no existing thing, and on the other hand, to seek to define in terms of the individual species without taking into account such a common definition. There is indeed a likeness between what holds of figures and what holds of the soul. For that which is prior is always potentially in that which is subsequent in both figures and ensouled beings, such as the triangle is in the square, and the vegetative in the sensitive.

279. Of the soul’s powers already spoken of (414a29). After defining the soul in general, Aristotle comes to treat of its parts. Now, the soul has no parts except in the sense that its powers are said to be parts of it, in that one subject, being in potency to many activities, its capacities with respect to each in particular can be called parts of it. To treat of the soul’s parts, then, is to treat of its various powers. This he does here in two main sections:

the first determines the soul’s powers in general and their distinction from one another;

the second, at we must first speak (415a22; [309]), takes them one by one.

The former subdivides into two:

first, a division of the powers of the soul;

and second, at so we must inquire (414b32; [299]), a discussion of what has to be determined about them, and how, and in what order.

Concerning the first, he does two things.

First, he distinguishes the powers of the soul.

Second, at it is, therefore, clear (414b19; [295]), he shows how the common account of the soul is related to the aforementioned parts.

Concerning the first, he does two things:

he first enumerates the powers of the soul;

and second, he shows how they are related to each other, at in plants there is (414a32; [288]).

First of all, then, he observes that, of the powers already enumerated, all are in some beings (men); some are in some (the other animals); and one only is in some others (plants). (Lect. 3, nn. 255, 260, 263.) And having previously called them not “powers” but “parts” of the soul, he makes it clear that he understands the same thing by “powers” here that he meant by “parts.” Now, of these there are five genera: the vegetative, sensitive, appetitive, locomotive, and intellectual.

280. Regarding this fivefold division, two things must be made clear:

first, why the customary threefold division of the soul into vegetative, sensitive, and rational is set aside so as to give this fivefold division of the genera of the soul’s powers.

and second, why he here presents five when has already made only a fourfold division.

281. As to the first, we should note that, because all potencies are spoken of in reference to their proper acts, active potencies are spoken of in reference to the act that is activity. Now, the soul’s potencies are active, for this sort of potency belongs to a form; hence, by differences between the soul’s activities we have to differentiate between its potencies. The activity of the soul, however, is the activity of a living thing.

Now, as the proper activity of anything belongs to it insofar as it has existence, because each thing acts insofar as it is a being, we have to study the soul’s activities precisely insofar as it is found in the living beings.

282. However, lower living things, whose actuality is soul (which is the subject of the present discussion), have existence in two ways: one, material, in which they fit with all other material things; and the other, immaterial, by which they have in some way something in common with higher substances.

283. Now, there is this difference between these two divisions of existence: insofar as its existence is material, which is restricted by its matter, each reality is only the thing it is, for example, this stone is nothing other than this stone; but insofar as its existence is immaterial, which has breadth and is in a certain way infinite insofar as it is not bounded by matter, the reality is not only the thing it is, but is in a certain way other things as well. That is why everything preexists, somehow, in the higher immaterial substances, as in universal causes.

284. But in lower things, immaterial existence has two degrees. For there is a certain thoroughly immaterial existence, that is, intelligible existence; for in the intellect, things have existence not only without matter but even without their individuating material conditions, and also apart from any bodily organ.

However, sensible existence is intermediate between each. For in sensing, a thing has existence apart from its matter, yet not without matter’s individuating conditions, nor apart from a bodily organ. For sensation is of particular things, but understanding is of universals. It is with reference to these two modes of existence that the Philosopher will say, in book 3, that the soul is somehow all things. (3.7, 431b21; cf. bk. 3, lect. 7, nn. 787–88, 790.)

285. The activities, therefore, that belong to living things according to their material existence are those we attribute to the vegetative soul. Yet even though they are ordered to what the actions of non-souled beings are ordered, that is, to attain and maintain existence, nonetheless in living things this occurs in a higher and nobler way.

For bodies that do not have souls are generated and maintained by an exterior moving principle, whereas ensouled bodies are generated by an intrinsic principle that is in the seed and are maintained in existence by an intrinsic nutritive principle. For it seems proper to living things that their activities should thus proceed from within themselves. But the purely immaterial activities of living things pertain to the intellectual part of the soul, while those attributed to them according to the intermediate existence pertain to its sensitive part. Hence it is usual to distinguish generally three souls: vegetative, sensitive, and rational.

286. But since everything exists according to some form, sensible existence exists according to a sensible form, and intelligible existence according to an intelligible form. Now, from every form follows a certain inclination, and from the inclination follows an activity, just as from the form of fire follows the inclination to an upper place (according to which fire is said to be light), and from this inclination follows the activity, that is, the movement upwards. Therefore on both the sensible and the intellectual form follows a certain inclination that is called the sensitive or intellectual appetite, just the inclination following on a natural form is called a natural appetite, from which appetite, moreover, follows the activity that is local motion. Here, then, is the explanation we required of the fivefold division of the genera of the powers of soul.

287. And as to the second point, note that when Aristotle wished to show that soul was the principle of living in all things that live, he divided living itself according to the grades of living things, and not according to the activities of life, according to which these genera of the powers are distinguished. Moreover, since all things that sense also have appetite, the appetitive does not constitute a distinct grade among living being; so we are left with only four such grades given above. (Lect. 3, nn. 253–60.)

288. Then, at in plants there is only (414a32), he shows how the powers of the soul follow upon one another, thus explaining what he said previously, that all these powers are present in (414a29) some things, some of them in some, and only one in yet others. (Lect. 4, n. 270.) Here we have to consider that the completeness of the universe requires that there should be no gaps in its order; rather, nature proceeds by degrees from the less to the more perfect. Hence, in Metaphysics 8, Aristotle likens the species of things to numbers, which increase by degrees, one by one. (Aristotle, Metaphysics 8.3, 1043b36–1044a2; cf. Aquinas, Commentary on Metaphysics, bk. 8, lect. 3, nn. 1723–24.)

Thus, among living things, there are some, that is, plants, which have only the vegetative capacity—which, indeed, all material living things must have because the activities pertaining to material being are attributed to this power.

Next are the animals, with the sensitive power as well as the vegetative; and if the sensitive power is there, there must be a third power, appetite, which itself divides into three: desire, which springs from the concupiscible power; anger, which springs from the irascible power—both of these appetites pertain to the sensitive part for they follow on sensory apprehension; and finally, will, which is the intellectual appetite, that is, what follows intellectual apprehension.

289. That appetite exists in all animals he demonstrates in two ways.

First, all animals have at least one sense, touch; but where there is any sensation there is joy and sorrow, that is, pleasure and pain. For while joy and sorrow seem to follow an inward apprehension, pain and pleasure follow on sensory apprehension, and especially the sense of touch. But if joy and sorrow are there, so must be the agreeable and disagreeable object, that is, something pleasant and painful. For everything sensed according to touch is either suitable to the one touching, and then it gives pleasure, or harmful, and then it gives pain. But whatever can feel pleasure and pain has desire, which is the appetite for the pleasant. Since, then, all animals, from the first to the last, have a sense of touch, all have appetite.

290. The second argument begins at further, all have (414b6), and runs thus. All animals have the sense that is aware of its own food, and this is the sense of touch. And because it is necessary for all animals to use food, as was said, it is therefore necessary that they have the sense of touch by which they perceive the food that is fitting to them. (Lect. 3, nn. 257–58.)

The fact that it is touch that is the sense of food is clear if we consider that, as living bodies are made up of warm, moist, cold, and dry elements, it is by these that they are nourished; and these elements are just what touch discerns. But other sense-objects, he says, do not, save accidentally, nourish living bodies; they do so only so far as they are involved in the objects of touch. Sound, color, and smell contribute nothing to nutrition as such; they occur in food only insofar as things that sound or are colored or odorous are also hot or cold, moist or dry. However, the moist, that is, savor, is something belonging to the number of the qualities of the objects of touch, so that tasting is a sort of touch. Clearly, then, all animals have a sense-awareness of food.

291. But whatever has this sensation of its food can feel hunger and thirst, each of which is a desire for food. Hunger is desire for the hot and the dry, what has the account of food; thirst for the cold and wet, what has the account of drink. Savor, however, is something delectable in these things, for a pleasing savor indicates a fitting proportion of the hot and the cold, the moist and the dry in the food. This is why it pertains more to the pleasure of food than to its necessity. Wherever there is the sense of touch, then, in this way there is appetite.

292. How imagination relates to the appetitive and sensitive powers will be shown later. (Lect. 29.)

293. Now, besides these three, the vegetative, the sensitive, and the appetitive, some animals, again, have the capacity to move from one place to another. In addition to these four capacities, intellect and understanding are also present in some, that is, in men and if there is something else, another genus of beings that is like human beings, or one even more excellent than human beings. The more excellent beings are the separated substances and the heavenly bodies—the latter, however, only if they are alive. Among mortal living beings, there is no genus of living things that have intellect except within the human species.

294. For because intellect has no bodily organ, beings that have intellect cannot be differentiated according to a diversity in the constitution of organs, as are the different species of animals (whose different constitutions cause them to have the activities of sensation in different ways).

295. Then, at it is, therefore, clear (414b19), he shows how his definition of soul is related to the parts that we have enumerated.

To understand this we must remember that Plato asserted that universals were separated according to their existence, yet he did not assert an idea for things that stand in this consequent relation, as do numbers and figures. For he did not say there is an idea of number beyond all the numbers, the way he said there is an idea of man beyond all men, because the species of numbers stand in a successive order, and the first of these, duality, is the cause of all that come after it; this is why there is no need to posit a common idea of number as the cause of the species of numbers. And a similar argument applies to figures, for they follow each other as do the species of numbers; from the triangle comes the square, and from the latter, the pentagon.

296. Aristotle then says that it is clear that the account of soul must be one in the same way as the account of figure is one. For just as, among figures, there is no figure existing apart from the triangle and the consequent species, as the common idea of all figures, so too is there no soul that stands, as it were, existing in separation, apart from the aforesaid parts.

297. But although there is (even for the Platonists who posit common separated species) no figure separated in being outside all the figures, nevertheless there is found one account common to all figures, which is not proper to any particular one of them. And the same is true of animals. It would be ludicrous, therefore, for a man to seek one common account, whether of animals or anything else, that did not belong to any of the souls that are in the nature of things as particular.

On the other hand, it will not do to seek the definition of soul in reference to each species of soul and reject a definition that is common to all souls. Therefore one should omit neither a common definition of soul nor should one designate a common definition of soul that does not belong to the individual souls.

298. And since he had said that the account of the soul stands in the same way as the account of figure, he shows the congruence between them, and says that a likeness regarding what holds for figures and souls in relation to each other. For in both cases what is prior exists in potency in that which is subsequent. For it is manifest that, in figures, the three-sided figure, which is prior, exists potentially in the square, for the square is divisible into two triangles. Likewise in the soul, the sensitive contains the vegetative as a certain power of it, and not as a soul through itself. The same holds good with the other figures and the other parts of soul.