Thomas Aquinas

“ The aspect of causality is perceived by comparing one thing to another, and in such a comparison the idea of good is found to be nobler: but truth signifies something more absolute, and extends to the idea of good itself: wherefore even good is something true. But, again, truth is something good: forasmuch as the intellect is a thing, and truth its end. And among other ends this is the most excellent: as also is the intellect among the other powers. ”

“ Thus, for instance, I might say that hearing is relatively nobler than sight, inasmuch as something in which there is sound is nobler than something in which there is color, though color is nobler and simpler than sound. ”

“ The mover, then, of necessity causes movement in the thing movable, when the power of the mover exceeds the thing movable, so that its entire capacity is subject to the mover. But as the capacity of the will regards the universal and perfect good, its capacity is not subjected to any individual good. And therefore it is not of necessity moved by it.
Reply to Objection 3: The sensitive power does not compare different things with each other, as reason does: but it simply apprehends some one thing. Therefore, according to that one thing, it moves the sensitive appetite in a determinate way. ”

“ There is no need to go on indefinitely, but we must stop at the intellect as preceding all the rest. For every movement of the will must be preceded by apprehension, whereas every apprehension is not preceded by an act of the will ”

“ Further, as is commonly said, charity is in the concupiscible, and hope in the irascible part. But they cannot be in the sensitive appetite, because their objects are not sensible, but intellectual. Therefore we must assign an irascible and concupiscible power to the intellectual part. ”

“ Now that a thing must be may belong to it by an intrinsic principle---either material, as when we say that everything composed of contraries is of necessity corruptible---or formal, as when we say that it is necessary for the three angles of a triangle to be equal to two right angles. ”