The purpose of life is not to be happy. It is to be useful, to be honorable, to be compassionate, to have it make some difference that you have lived and lived well.

The best preparation for good work tomorrow is to do good work today.

这个世界惟有两样东西让我们的心灵感到深深的震撼，一是我们头顶上灿烂的星空，一是我们内心崇高的道德法则。

一切皆有可能，但没有什么是一定的。

God loves man's lamp-lights better than his own great stars。