贫困和无知可能逐渐消失的希望，很大程度上源于十九世纪工人阶级的稳步进步。

真理是不朽的，它超越了时间的局限。

快乐的最好方法是做你自己。

The most important thing in science is not so much to obtain new facts as to discover new ways of thinking about them.

"The world is a book, and those who do not travel read only one page."

办一件事都不能善始善终，就不要做很多事。