Three things are necessary for the salvation of man: to know what he ought to believe; to know what he ought to desire; and to know what he ought to do.
Thomas AquinasGive us, O Lord, a steadfast heart, which no unworthy affection may drag downwards; give us an unconquered heart, which no tribulation can wear out; give us an upright heart, which no unworthy purpose may tempt aside. Bestow upon us also, O Lord our God, understanding to know you, diligence to seek you, wisdom to find you, and a faithfulness that may finally embrace you; through Jesus Christ our Lord.
Thomas AquinasWe must love them both, those whose opinions we share and those whose opinions we reject, for both have labored in the search for truth, and both have helped us in finding it.
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 AquinasWithout doubt one is allowed to resist against the unjust aggressor to one's life, one's goods or one's physical integrity; sometimes, even 'til the aggressor's death... In fact, this act is aimed at preserving one's life or one's goods and to make the aggressor powerless. Thus, it is a good act, which is the right of the victim.
Thomas Aquinas