The only limit to our realization of tomorrow is our doubts of today.

No arts; no letters; no society; and which is worst of all, continual fear and danger of violent death; and the life of man, solitary, poor, nasty, brutish, and short.

凡是做学问，必须从各个方面都理解透彻，还要更进一步深入理解内在的道理。

生命太短暂，不能随波逐流。