e [*See
Objection 1], the voluntary is defined not only as having "a principle
within" the agent, but also as implying "knowledge." Therefore, since
man especially knows the end of his work, and moves himself, in his
acts especially is the voluntary to be found.

Reply Obj. 1: Not every principle is a first principle. Therefore,
although it is essential to the voluntary act that its principle be
within the agent, nevertheless it is not contrary to the nature of
the voluntary act that this intrinsic principle be caused or moved by
an extrinsic principle: because it is not essential to the voluntary
act that its intrinsic principle be a first principle. Yet again it
must be observed that a principle of movement may happen to be first
in a genus, but not first simply: thus in the genus of things subject
to alteration, the first principle of alteration is a heavenly body,
which nevertheless is not the first mover simply, but is moved
locally by a higher mover. And so the intrinsic principle of the
voluntary act, i.e. the cognitive and appetitive power, is the first
principle in the genus of appetitive movement, although it is moved
by an extrinsic principle according to other species of movement.

Reply Obj. 2: New movements in animals are indeed preceded by a
motion from without; and this in two respects. First, in so far as by
means of an extrinsic motion an animal's senses are confronted with
something sensible, which, on being apprehended, moves the appetite.
Thus a lion, on seeing a stag in movement and coming towards him,
begins to be moved towards the stag. Secondly, in so far as some
extrinsic motion produces a physical change in an animal's body, as
in the case of cold or heat; and through the body being affected by
the motion of an outward body, the sensitive appetite which is the
power of a bodily organ, is also moved indirectly; thus it happens
that through some alteration in the body the appetite is roused to
the desire of something. But this is not contrary to the nature of
voluntariness, as stated above (ad 1), for such movements caused by
an extrinsic principle are of another genus of movement.

Reply Obj. 3: God moves man to act, not only by proposing the
appetible to the senses, or by effecting a change in his body, but
also by moving the will itself; because every movement either of the
will or of nature, proceeds from God as the First Mover. And just as
it is not incompatible with nature that the natu