“1), love consists in a certain agreement of the lover with the object loved, while hatred consists in a certain disagreement or dissonance. Now we should consider in each thing, what agrees with it, before that which disagrees: since a thing disagrees with another, through destroying or hindering that which agrees with it. Consequently love must needs precede hatred; and nothing is hated, save through being contrary to a suitable thing which is loved. And hence it is that every hatred is caused by love.
Reply Obj. 1: The opposite members of a division are sometimes naturally simultaneous, both really and logically; e.g. two species of animal, or two species of color. Sometimes they are simultaneous logically, while, in reality, one precedes, and causes the other; e.g.”