The mathematician's patterns, like the painter's or the poet's, must be beautiful; the ideas, like the colors or the words, must fit together in a harmonious way.

智者从敌人那里学到的比愚者从朋友那里学到的还要多。

The past shapes the present, and the present shapes the future.

The only sensible ends of literature are, first, the pleasurable toil of writing; second, the gratification of one's family and friends; and lastly, the solid cash.