summa-contra-gentiles

236 THE SUMMA CONTRA GENTILES
objects of intelligence, is able to understand others, not less
but more.^ Consequently the passion caused in the sense
by the sensible differs in kind from that which is caused in
the intellect by the intelligible the passion of the intellect
:
occurring without a corporeal organ, while the passion of
the sense is connected with a corporeal organ, the harmony
of which is destroyed by the excellence of the sensible.
Plato's statement that a soul moves itself may seem to be
well founded by reason of what we observe in regard to
bodies. For seemingly no body moves unless it is moved :
wherefore Plato said that every mover is moved. And since
we cannot go on to infinity as though every thing moved
were moved by another, he stated that in each order the
first mover moved itself. From this it followed that the
soul, which is the first mover in the movement of animals,
is
something that moves itself.
But this is shown to be false, on two counts. First,
because it has been proved^ that whatever is moved per se
is a body : wherefore, since a soul is not a body,
impossible for it to be moved save accidentally.
it is
Secondly, because, since a mover, as such, is in act,
while the thing moved, as such, is in potentiality, and since
nothing can be, in the same respect, in act and potentiality ;
it will be impossible for the same thing to be, in the same
respect, mover and moved, but if a thing
is stated to move
one part thereof must needs be mover and the other
itself,
part moved. It is in this way that an animal is said to
move itself, because the soul is mover and the body moved.
Since, however, Plato did not hold that the soul is a body,
although he made use of the word movement which
properly speaking belongs to bodies, he did not mean
movement in this strict sense but referred it in a more
general way to any operation also says (3 De AnimaY that sensation and understanding
are movements : but in this way movement is the act, not of
: in which sense Aristotle
that which is in potentiality but of that which is perfect.
Consequently, when he said that the soul moves itself, by
^ S De Anima iv. 5. * Bk. I., ch. xiii.
' vii. i, 2.