On The Soul
latter an animals, and not only man, partake.
We must consider also in the case of imperfect animals, sc. those
which have no sense but touch, what it is that in them originates
movement. Can they have imagination or not? or desire? Clearly they
have feelings of pleasure and pain, and if they have these they must
have desire. But how can they have imagination? Must not we say
that, as their movements are indefinite, they have imagination and
desire, but indefinitely?
Sensitive imagination, as we have said, is found in all animals,
deliberative imagination only in those that are calculative: for
whether this or that shall be enacted is already a task requiring
calculation; and there must be a single standard to measure by, for
that is pursued which is greater. It follows that what acts in this
way must be able to make a unity out of several images.
This is the reason why imagination is held not to involve opinion,
in that it does not involve opinion based on inference, though opinion
involves imagination. Hence appetite contains no deliberative element.
Sometimes it overpowers wish and sets it in movement: at times wish
acts thus upon appetite, like one sphere imparting its movement to
another, or appetite acts thus upon appetite, i.e. in the condition of
moral weakness (though by nature the higher faculty is always more
authoritative and gives rise to movement). Thus three modes of
movement are possible.
The faculty of knowing is never moved but remains at rest. Since the
one premiss or judgement is universal and the other deals with the
particular (for the first tells us that such and such a kind of man
should do such and such a kind of act, and the second that this is
an act of the kind meant, and I a person of the type intended), it
is the latter opinion that really originates movement, not the