Summa Theologica, Part I (Prima Pars) From the Complete...

Reply Obj. 2: What precedes in order of generation and time is less perfect: for in one and in the same thing potentiality precedes act, and imperfection precedes perfection. But what precedes absolutely and in the order of nature is more perfect: for thus act precedes potentiality. And in this way the intellect precedes the will, as the motive power precedes the thing movable, and as the active precedes the passive; for good which is understood moves the will.

Objection 1: It would seem that the will does not move the intellect. For what moves excels and precedes what is moved, because what moves is an agent, and "the agent is nobler than the patient," as Augustine says (Gen. ad lit. xii, 16), and the Philosopher (De Anima iii, 5). But the intellect excels and precedes the will, as we have said above (A. 3). Therefore the will does not move the intellect.

Obj. 2: Further, what moves is not moved by what is moved, except perhaps accidentally. But the intellect moves the will, because the good apprehended by the intellect moves without being moved; whereas the appetite moves and is moved. Therefore the intellect is not moved by the will.

Obj. 3: Further, we can will nothing but what we understand. If, therefore, in order to understand, the will moves by willing to understand, that act of the will must be preceded by another act of the intellect, and this act of the intellect by another act of the will, and so on indefinitely, which is impossible. Therefore the will does not move the intellect.

I answer that, A thing is said to move in two ways: First, as an end; for instance, when we say that the end moves the agent. In this way the intellect moves the will, because the good understood is the object of the will, and moves it as an end. Secondly, a thing is said to move as an agent, as what alters moves what is altered, and what impels moves what is impelled. In this way the will moves the intellect and all the powers of the soul, as Anselm says (Eadmer, De Similitudinibus). The reason is, because wherever we have order among a number of active powers, that power which regards the universal end moves the powers which regard particular ends. And we may observe this both in nature and in things politic. For the heaven, which aims at the universal preservation of things subject to generation and corruption, moves all inferior bodies, each of which aims at the preservation of its own species or of the individual. The king also, who aims at the common good of the whole kingdom, by his rule moves all the governors of cities, each of whom rules over his own particular city. Now the object of the will is good and the end in general, and each power is directed to some suitable good proper to it, as sight is directed to the perception of color, and the intellect to the knowledge of truth. Therefore the will as agent moves all the powers of the soul to their respective acts, except the natural powers of the vegetative part, which are not subject to our will.

Reply Obj. 1: The intellect may be considered in two ways: as apprehensive of universal being and truth, and as a thing and a particular power having a determinate act. In like manner also the will may be considered in two ways: according to the common nature of its object—that is to say, as appetitive of universal good—and as a determinate power of the soul having a determinate act. If, therefore, the intellect and the will be compared with one another according to the universality of their respective objects, then, as we have said above (A. 3), the intellect is simply higher and nobler than the will. If, however, we take the intellect as regards the common nature of its object and the will as a determinate power, then again the intellect is higher and nobler than the will, because under the notion of being and truth is contained both the will itself, and its act, and its object. Wherefore the intellect understands the will, and its act, and its object, just as it understands other species of things, as stone or wood, which are contained in the common notion of being and truth. But if we consider the will as regards the common nature of its object, which is good, and the intellect as a thing and a special power; then the intellect itself, and its act, and its object, which is truth, each of which is some species of good, are contained under the common notion of good. And in this way the will is higher than the intellect, and can move it.

From this we can easily understand why these powers include one another in their acts, because the intellect understands that the will wills, and the will wills the intellect to understand. In the same way good is contained in truth, inasmuch as it is an understood truth, and truth in good, inasmuch as it is a desired good.

Reply Obj. 3: There is no need to go on indefinitely, but we must stop at the intellect as preceding all the rest. For every movement of the will must be preceded by apprehension, whereas every apprehension is not preceded by an act of the will; but the principle of counselling and understanding is an intellectual principle higher than our intellect—namely, God—as also Aristotle says (Eth. Eudemic. vii, 14), and in this way he explains that there is no need to proceed indefinitely. _______________________

Objection 1: It would seem that we ought to distinguish irascible and concupiscible parts in the superior appetite, which is the will. For the concupiscible power is so called from "concupiscere" (to desire), and the irascible part from "irasci" (to be angry). But there is a concupiscence which cannot belong to the sensitive appetite, but only to the intellectual, which is the will; as the concupiscence of wisdom, of which it is said (Wis. 6:21): "The concupiscence of wisdom bringeth to the eternal kingdom." There is also a certain anger which cannot belong to the sensitive appetite, but only to the intellectual; as when our anger is directed against vice. Wherefore Jerome commenting on Matt. 13:33 warns us "to have the hatred of vice in the irascible part." Therefore we should distinguish irascible and concupiscible parts of the intellectual soul as well as in the sensitive.

Obj. 2: Further, as is commonly said, charity is in the concupiscible, and hope in the irascible part. But they cannot be in the sensitive appetite, because their objects are not sensible, but intellectual. Therefore we must assign an irascible and concupiscible power to the intellectual part.

Obj. 3: Further, it is said (De Spiritu et Anima) that "the soul has these powers"—namely, the irascible, concupiscible, and rational—"before it is united to the body." But no power of the sensitive part belongs to the soul alone, but to the soul and body united, as we have said above (Q. 78, AA. 5, 8). Therefore the irascible and concupiscible powers are in the will, which is the intellectual appetite.

On the contrary, Gregory of Nyssa (Nemesius, De Nat. Hom.) says that the irrational part of the soul is divided into the desiderative and irascible, and Damascene says the same (De Fide Orth. ii, 12). And the Philosopher says (De Anima iii, 9) "that the will is in reason, while in the irrational part of the soul are concupiscence and anger," or "desire and animus."

I answer that, The irascible and concupiscible are not parts of the intellectual appetite, which is called the will. Because, as was said above (Q. 59, A. 4; Q. 79, A. 7), a power which is directed to an object according to some common notion is not differentiated by special differences which are contained under that common notion. For instance, because sight regards the visible thing under the common notion of something colored, the visual power is not multiplied according to the different kinds of color: but if there were a power regarding white as white, and not as something colored, it would be distinct from a power regarding black as black.

Now the sensitive appetite does not consider the common notion of good, because neither do the senses apprehend the universal. And therefore the parts of the sensitive appetite are differentiated by the different notions of particular good: for the concupiscible regards as proper to it the notion of good, as something pleasant to the senses and suitable to nature: whereas the irascible regards the notion of good as something that wards off and repels what is hurtful. But the will regards good according to the common notion of good, and therefore in the will, which is the intellectual appetite, there is no differentiation of appetitive powers, so that there be in the intellectual appetite an irascible power distinct from a concupiscible power: just as neither on the part of the intellect are the apprehensive powers multiplied, although they are on the part of the senses.

Reply Obj. 1: Love, concupiscence, and the like can be understood in two ways. Sometimes they are taken as passions—arising, that is, with a certain commotion of the soul. And thus they are commonly understood, and in this sense they are only in the sensitive appetite. They may, however, be taken in another way, as far as they are simple affections without passion or commotion of the soul, and thus they are acts of the will. And in this sense, too, they are attributed to the angels and to God. But if taken in this sense, they do not belong to different powers, but only to one power, which is called the will.

Reply Obj. 2: The will itself may be said to [be] irascible, as far as it wills to repel evil, not from any sudden movement of a passion, but from a judgment of the reason. And in the same way the will may be said to be concupiscible on account of its desire for good. And thus in the irascible and concupiscible are charity and hope—that is, in the will as ordered to such acts. And in this way, too, we may understand the words quoted (De Spiritu et Anima); that the irascible and concupiscible powers are in the soul before it is united to the body (as long as we understand priority of nature, and not of time), although there is no need to have faith in what that book says. Whence the answer to the third objection is clear. _______________________