世界是一本书，不旅行的人只读了一页。

The right of nature... is the liberty each man hath, to use his own power, as he will himself, for the preservation of his own nature; that is to say, of his own life.

理论物理学是一种形而上学。

从长远来看，未来是由乐观主义者决定的。成为一个乐观主义者，不是要忽视现有的许多问题，而是想象怎么才能改善我们解决问题的能力。