按照我们的本性行事就是美德。

最大的恐惧不是死亡，而是生活。

The laws that forbid the carrying of arms are laws of such a nature. They disarm only those who are neither inclined nor determined to commit crimes.... Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man.

数学的真正乐趣在于发现的过程，而不仅仅是结果。