Lecture 6 — Interrelation and definition of the soul’s powers

So we must inquire in each particular case what the soul is in plants, what is it for men, and what it is for beasts.

It must be considered why they stand in this order, for there is no sensitive soul without the vegetative, yet in plants the vegetative exists apart from the sensitive. Again, there can be no sense apart from what can touch, but touch exists without the others; for many animals have no sight or hearing or sense of smell. Again, among sentient beings, some have local motion, others not. Last and least extensive of all is that of the one that reasons and understands (as man and any other such). For among corruptible beings, reasoning is present in certain ones along with all the rest of the powers, but reason is not found in all those that have any one of the latter; some indeed have not even imagination, and others live by this alone. However, the account of the speculative intellect is different.

Clearly, then, whatever is the most proper account with respect to each of the above will also be that of the soul.

It is necessary for those making an inquiry of these things to take up what each of these is, and only then to investigate habits and other matters.

But if one is to say what each of them is (namely, the intellectual power or the sensitive or the vegetative), one must first say what it is to understand and what it is to sense, for acts and activities are prior to potencies in account. And if this is so, one ought before that to consider their objects; for the same reason it will be necessary to determine, in the first place, what these things are—for instance, food, the sensible, and the intelligible.

299. So we must inquire in each particular case (414b32). After enumerating the genera of the powers of the soul and showing how the common definition given above is related to the particular parts of soul, now the Philosopher shows what should be determined and in what order, and this is divided into two parts. (Lect. 1, n. 233.)

First, he explains what remains to be determined about the soul;

second, he explains in what order, at it is necessary for those making an inquiry (415a14 [303]).

There are, he says, still two points to be made clear, one of which follows from the argument just given.

For we have seen that, just as we must not be satisfied with the sort of common definition of soul that belongs to none of the particular souls, so too, we cannot rest content even with the common definition; (Lect. 5, n. 297.) rather, it is necessary to inquire into a proper definition of each part of the soul, and from this he concludes that we must inquire in each particular case what the soul is, so that one might know what the soul of a plant is, what the soul of a man is, and what the soul of a beast is—and this is to know what each part of the soul is.

300. Then, at it must be considered (414b33), he states the next point to be decided. He has already said that the parts of the soul stand or follow each other in a series like the species of figure; and it must be considered why. (Lect. 5, nn. 295–98.) This reason will be given at the end of the treatise; here he only shows how the parts of soul follow one from the other successively. (Bk. 3, lect. 11–12.) For the sensitive, he says, cannot exist without the vegetative, but the latter can, in plants, exist without the sensitive. And this is not surprising; for, as we have seen, the works of the vegetative activities are ordered to attaining and retaining natural existence, which underlies as the foundation of all the rest. (Lect. 5, n. 285.)

And again, the senses themselves display a like sequence; there can be no sense at all unless there is touch; but touch exists without the others. For many animals have no sight, or hearing, or sense of smell, but only touch. And this will appear quite reasonable if we consider that touch is the sense that is perceptive of the things of which the animal consists (that is, what the animal is composed of and is nourished by); other sensible things do not contribute to this except accidentally. Hence the other senses are not necessary for an animal, and on account of this they are not found in all animals, but only in the perfect ones.

301. Again, one must consider the connection between the sensitive and motive powers. For the motive power cannot exist without the sensitive, but the sensitive can be without the motive. For some of the things that have sense also have local motion, others not. We are speaking of the progressive movement of animals, whereby they move from one place to another; for this motion is not in all animals, though things that lack it have a certain local movement, that of expansion and contraction—this is apparent in shellfish.

The last among the parts of the soul—and the least extensive since it is not subdivided into different species—is that which has the reason and understands; because for whatever among the number of corruptible beings reason is found present in, there are found all the rest of the aforesaid powers.

He speaks this way to exclude separated substances and the heavenly bodies (if these are ensouled), since, as they exist apart from generation and corruption, they do not need the vegetative power; moreover, their intellect contemplates through itself things that are intelligible through themselves, so they do not require senses for attaining intellectual knowledge. But in mortal natures that have understanding, it is necessary that all the others preexist as certain instruments and as preparatory for intellect, which is the final perfection intended in the activity of nature.

But not all which have these other powers also have reason. And because of the affinity between intellect and imagination—as he said above, intellect either is, or never occurs without, a certain imagination (403a5)—he adds this about imagination, saying that some animals lack not only intellect but even imagination. (Bk. 1, lect. 2, n. 18.)

302. Yet this might seem to contradict a previous remark of his, that if a part cut from an animal retains sensation and appetite, it retains also imagination—if phantasia is the same thing as imagination, as seems likely. (Lect. 4, n. 265.)

We must, therefore, say that the imperfect animals have indeed a sort of imagination, but indeterminately, as will be shown in book 3; (3.10, 433b31–434a5; cf. lect. 29, n. 644; bk. 3, lect. 10, n. 839.) that is, the motion of imagining does not, in them, outlast the apprehension of sensation; in the perfect animals, however, the motion of imagination remains even when the sensible things are gone. And in this sense he says here that imagination is not present in all animals.

Some animals, lacking intellect, live by this alone (414b33), by imagination, being directed in their activities by their imagination just as we are directed by our intellect. And though certain other animals lack both imagination and intellect, nevertheless the account of the speculative intellect is not the same as that of the imagination, as we shall see. (Bk. 3, lect. 7, n. 793.) Clearly, then (415a12), this definition of the soul which has been given is said most properly for each part of the soul.

303. Then, at it is necessary (415a14), he shows the order to be followed in examining the parts of soul. And he does so with regard to two things.

First, with respect to one’s needing to study the parts of the soul, the first thing to do is to take up what each of these is and only then should one consider their habits, that is, whatever other parts of soul derive from them, and other matters pertaining to the soul’s parts and the very things that are ensouled, like the organs and things of that kind. And this order is necessary, because it would be confusing to learn if everything were discussed at once.

304. Then, at but if (415a16), he considers the second, saying that, if one is to say of any part of the soul what each of them is—that is, the intellectual power or the sensitive or the vegetative—one must first say this of their acts, for example, what it is to understand and what it is to sense; because in account, acts and activities are prior to potencies. For a potency in virtue of its very self brings in a certain orientation to act, for it is a principle of acting or of being acted upon; this is why acts must be placed in the definitions of potencies. And if this is the case with the order of act and potency, the objects are before even the acts.

305. For the species of acts and activities are taken in reference to their objects. For every activity of the soul is the act of either an active potency or a passive potency.

Now, the objects of passive potentialities stand to their activities as the agents, since they bring the potencies to act; for example, visible objects do so for sight, as does every sensible for its sense.

But the objects of the active capacities stand to their activities themselves as ends, for the objects of active potencies are their works. It is obvious, however, that whenever activities bring about anything besides the activities themselves, the things brought about are the ends of the activities, as is said in Ethics 1; for example, a house is the end of building. (Aristotle, Ethics 1.1, 1094a5–6; cf. Aquinas, Commentary on Ethics, bk. 7, lect. 10.)

Hence, all the objects of the soul’s activities are compared to the soul’s activities as either agents or ends; and in both respects they specify those activities. For, obviously, specifically diverse agents have specifically diverse activities—as heat heats and cold chills. So too, the terminus and end of activity specifies the activity: for example, becoming well or becoming ill differ in species because health differs from illness. Thus, in the path of seeking definitions, the objects of the soul’s activities are before these activities.

306. Therefore, it will be necessary to determine their objects before the activities for the same reason that leads us to determine the activities before the potencies. The objects in question are such things as food and sensible being and intelligible being, with respect to the vegetative, sensitive, and intellectual powers, respectively.

307. But note that the acts and powers of soul are not distinguished with respect to distinct objects except precisely insofar as these are objects, that is, according to the formal account of the object, as the visible differs from the audible. But if the same account of object is present, then it does not matter what other differences there may be; they will not affect the species of activity or potency. For by the same power we see a colored man and a colored stone; the difference is merely accidental to the object as object.

308. Now, it should be known that our potential intellect is in potency only in the order of intelligibles, but it comes into act through a form abstracted from phantasms. Nothing is known except in the degree that it is actual; hence, our potential intellect knows its very self only through an intelligible species (as will be explained in book 3) and not by directly intuiting its own essence. (3.3, 430a2–5; cf. bk. 3, lect. 3, nn. 724–26.) This is why in the process of knowing the soul we must proceed from quite exterior things, from which intelligible species are abstracted, in which it perceives itself; so we proceed through objects to acts, through acts to powers, and through powers to the essence of the soul. But if the soul could know its own essence directly through its very self, a contrary order would need to be followed in knowing the soul; for the closer anything might be to the soul’s essence, so in a prior way would it be known by it.