"given the nature of the human couple, the love of a man and a woman is a priori inferior to that which can exist (at least in the best instances) in the love between man and dog...It is a completely selfless love."

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She had never realized any love save love as passion. Such love, though it expends itself in generosity and thoughtfulness, though it give birth to visions and to great poetry, remains among the sharpest expressions of self-interest. Not until it has passed though a long servitude, though its own self-hatred, though mockery, though great doubts, can it take its place among the loyalties. Many who have spent a lifetime in it can tell us less of love than the child that lost a dog yesterday.

— Thornton Wilder