On The Motion Of Animals   

when the creature attains maturity; and therefore it is the cause of

growth, when the creature becomes the cause of its own growth, and the

cause too of alteration. But if this is not the primary movement

then the point at rest is not necessary. However, the earliest

growth and alteration in the living creature arise through another and

by other channels, nor can anything possibly be the cause of its own

generation and decay, for the mover must exist before the moved, the

begetter before the begotten, and nothing is prior to itself.

6



Now whether the soul is moved or not, and how it is moved if it be

moved, has been stated before in our treatise concerning it. And since

all inorganic things are moved by some other thing- and the manner

of the movement of the first and eternally moved, and how the first

mover moves it, has been determined before in our Metaphysics, it

remains to inquire how the soul moves the body, and what is the origin

of movement in a living creature. For, if we except the movement of

the universe, things with life are the causes of the movement of all

else, that is of all that are not moved by one another by mutual

impact. And so all their motions have a term or limit, inasmuch as the

movements of things with life have such. For all living things both

move and are moved with some object, so that this is the term of all

their movement, the end, that is, in view. Now we see that the

living creature is moved by intellect, imagination, purpose, wish, and

appetite. And all these are reducible to mind and desire. For both

imagination and sensation are on common ground with mind, since all

three are faculties of judgement though differing according to

distinctions stated elsewhere. Will, however, impulse, and appetite,

are all three forms of desire, while purpose belongs both to intellect

and to desire. Therefore the object of desire or of intellect first

initiates movement, not, that is, every object of intellect, only

the end in the domain of conduct. Accordingly among goods that which