Mathematics is not a careful march down a well-cleared highway, but a journey into a strange wilderness, where the explorers often get lost.

When you confront a stuck bolt or screw: righty tighty， lefty loosey.

〈与日人某君的谈话〉，1924年2月

Life is a dream for the wise, a game for the fool, a comedy for the rich, a tragedy for the poor.

气候变化是对全球渔业未来的最大威胁。