You don’t have to be perfect, just be real.
Westward the course of empire takes its way.
《在陆军军官学校开学典礼的演说》（1924年6月16日）
解释：既要追悔以往的过失，也要预防将来可能发生的错误。
The world is like a chessboard， whereon we may see a living knight， but we cannot see a living chess.
我已经不再年轻，不再无所不知。
"We are all astronauts on a little spaceship called Earth."