You cannot hope to build a better world without improving the individuals. To that end, each of us must work for our own improvement and, at the same time, share a general responsibility for all humanity, our particular duty being to aid those to whom we think we can be most useful.

时间旅行的难题在于，你无法前往自己不存在的地方。

科学的进步依赖于挑战权威的勇气。