伟大的工程是无形的——它只是无缝地运作。

热爱你过的生活，过你热爱的生活。

The most beautiful as well as the most ugly inclinations of man are not part of a fixed biologically given nature, but result from the social process which creates man.

乐观主义者认为这是所有可能世界中最好的一个。悲观主义者知道确实如此。