The dinosaurs became extinct because they didn't have a space program. And if we become extinct because we don't have a space program, it'll serve us right!

I don't need a reason to be happy. I choose to be.

I think goals should never be easy, they should force you to work, even if they are uncomfortable at the time.

正派人的话，明明知道了为了我好，内心感激却未必高兴；奸邪人的话，明明知道是在奉承我，但听着十分顺耳，所以未必生气。由此可知听取忠言是多么艰难。

如果你认为你理解了量子力学，那么你并没有真正理解量子力学。