CHAPTER X

THE PRINCIPLES OF MOVEMENT IN LIVING BEINGS CONTINUED

WHAT THEY ARE

             IT SEEMS THAT THERE ARE TWO MOTIVE-FORCES, MIND and appetency (if one is to account imagination a sort of mind. For many follow the imagination instead of intellectual knowledge, while in other animals there is no intellect or reason at all, but only imagination). Both of these effect movement in place then,--intellect and appetency.§§ 818-19

             Now, the intellectual power which reasons to some purpose in view, and is practical, differs in its end from the speculative. Appetition also is always for a purpose; for that of which there is desire is the principle of the practical intellect. The last end is the first principle of action. Hence, it seems reasonable to take these two as the motive forces, appetition, and the practical reason. For the object of appetite causes motion; and it is for this that reason also initiates movement, the desirable being its principle. And when imagination moves, it only does so with appetition. Therefore there is one single mover,--the object desired. For if there were two movers, intellect and appetition, they would move in virtue of some common principle. Now reason does not appear to cause movement apart from appetency; for will is an appetency. When there is movement by reason there is also movement by will. But appetition moves apart from reason, for concupiscence is a sort of appetition.§§ 820-5

             All intellect, then, is right, but imagination and appetition may be right or not right. Hence, while the object of appetite is always what motivates, this can be either a good or only a seeming good. Not, however, every good, but the practical good. Now a practical object is that which is able to be other than it is. It is therefore evident that what moves the soul is a power of this kind called appetite.§§ 826-7

             For those who divide the soul into parts, if they split it up by distinguishing its powers, a great many parts result: the vegetative, the sensitive, the intellective, the deliberative, and lastly the appetitive. These differ from one another much more than do the concupiscible and irascible.§ 828

             Since appetites may run counter to one another, this occurs when reason and desire are contrary (and only in beings possessing a time-sense. Reason commands restraint for the sake of some future thing, but desire is for what is now present. For what appears desirable at any given instant appears desirable without qualification and good without qualification; because the future is not apparent).§ 829

             The motive-force will therefore be specifically one,--the desirable, or the appetite itself; and first of all the desirable, for this is what causes motion without itself being moved, simply through being understood or imagined,--but numerically there are several moving factors.§ 830

             Since there are these three: the mover; secondly, that by which it moves; thirdly, that which is moved; and since the mover is double (the immobile one, and the mover that is also moved) the immobile mover is, accordingly, the practical good, whereas that which both moves and is moved is the appetite. For the subject desiring is moved in so far as it desires, and its desire is an act or movement of a certain kind. What receives the motion is the animal. But that by which it moves is an organ, already something corporeal. Hence, what pertains to it must be studied along with activities common to body and soul.§ 831

             Now, in short, organic movement arises where the principle and term are the same: as in the joint of a hinge are the convex and the concave,--the latter being the end, the former the beginning. Hence one is at rest while the other moves. They are distinct in idea, but inseparable spatially. All things move by pushing and pulling. Hence there must, as in a circle, be something that stays still; from which [point] movement begins.§§ 832-5