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