Good and evil are essential differences of the act of the will. For good and evil pertain essentially to the will; just as truth and falsehood pertain to the reason, the act of which is distinguished essentially by the difference of truth and falsehood (according as we say that an opinion is true or false.) Consequently, good and evil volition are acts differing in species.
Thomas AquinasPain itself can be pleasurable accidentally in so far as it is accompanied by wonder, as in stage-plays; or in so far as it recalls a beloved object to one's memory, and makes one feel one's love for the thing, whose absence gives us pain. Consequently, since love is pleasant, both pain and whatever else results from love, in so far as they remind us of our love, are pleasant.
Thomas AquinasThere would not be a perfect likeness of God in the universe if all things were of one grade of being.
Thomas AquinasAs regards the individual nature, woman is defective and misbegotten, for the active power of the male seed tends to the production of a perfect likeness in the masculine sex; while the production of a woman comes from defect in the active power.
Thomas AquinasA person is disposed to an act of choice by an angel ... in two ways. Sometimes, a man's understanding is enlightened by an angel to know what is good, but it is not instructed as to the reason why ... But sometimes he is instructed by angelic illumination, both that this act is good and as to the reason why it is good.
Thomas Aquinas