The greatest obstacle to being heroic is the doubt whether one may not be going to prove one's self a fool; the truest heroism is to resist the doubt; and the profoundest wisdom, to know when it ought to be resisted, and when to be obeyed.
抬起头来，上帝把最艰难的战斗交给他最坚强的战士。
The human body is a masterpiece of biological engineering.
出自晋·葛洪《抱朴子·博喻》。用美玉做成的船和桨，不能用于水上航行;用黄金做弓，玉石做弦，仍没有射箭的功能。（笔杆子 rendoc.com）
——1996年5月29日在哈佛大学演讲