The best science is done with both hands dirty and minds clear.

History does not long entrust the care of freedom to the weak or the timid.

To find out what one is fitted to do, and to secure an opportunity to do it, is the key to happiness.

写作的行为是一种乐观的行为。

道理明白了，文辞就能表达清楚；文辞表达清楚了，道理也就明白了。