快乐的最好方法是给予。

"The fundamental fact about all of us is that we're alive for a while but will die before long. This fact is the real root cause of all our anger and pain."

It is not from the benevolence of the butcher， the brewer， or the baker that we expect our dinner， but from their regard to their own interest.

A theory should not attempt to explain all the facts, because some of the facts are wrong.