not
speak of understanding with regard to things known through first
principles, except in so far as we see the principles in those things.
For in morals the end is what principles are in speculative science
(Ethic. viii, 8).

Reply Obj. 1: The Philosopher is speaking of the will in reference to
the simple act of the will; not in reference to the power of the will.

Reply Obj. 2: There are different powers for objects that differ in
genus and are on an equality; for instance, sound and color are
different genera of sensibles, to which are referred hearing and
sight. But the useful and the righteous are not on an equality, but
are as that which is of itself, and that which is in relation to
another. Now such like objects are always referred to the same power;
for instance, the power of sight perceives both color and light by
which color is seen.

Reply Obj. 3: Not everything that diversifies habits, diversifies the
powers: since habits are certain determinations of powers to certain
special acts. Moreover, every practical art considers both the end
and the means. For the art of the helmsman does indeed consider the
end, as that which it effects; and the means, as that which it
commands. On the other hand, the ship-building art considers the
means as that which it effects; but it considers that which is the
end, as that to which it refers what it effects. And again, in every
practical art there is an end proper to it and means that belong
properly to that art.
________________________

THIRD ARTICLE [I-II, Q. 8, Art. 3]

Whether the Will Is Moved by the Same Act to the End and to the Means?

Objection 1: It would seem that the will is moved by the same act, to
the end and to the means. Because according to the Philosopher (Topic.
iii, 2) "where one thing is on account of another there is only one."
But the will does not will the means save on account of the end.
Therefore it is moved to both by the same act.

Obj. 2: Further, the end is the reason for willing the means, just as
light is the reason of seeing colors. But light and colors are seen
by the same act. Therefore it is the same movement of the will,
whereby it wills the end and the means.

Obj. 3: Further, it is one and the same natural movement which tends
through the middle space to the terminus. But the means are in
comparison to the end, as the middle space is to the terminus.
Therefore it is the same movement of the will whereby it is directed
to