Every life leaves behind a trail of evidence; the biographer is the detective who follows it.

The only way to do great work is to love what you do.

人类的思想和行为是自然的一部分，因此可以通过自然科学的方法来研究。

有时候生活会给你当头一棒。不要失去信心。

我们的现代头颅里装着一个石器时代的心智。

Society can and does execute its own mandates， and if it issues wrong mandates instead of right， or any mandates at all in things with which it ought not to meddle， it practices a social tyranny more formidable than many kinds of political oppression， since， though not usually upheld by such extreme penalties， it leaves fewer means of escape， penetrating much more deeply into the details of life， and enslaving the soul itself.