As in geometry the most natural way of beginning is from a mathematical point, so is the same method in observations and natural history the most genuine, simple, and instructive.

"The past is never dead. It's not even past."

"A picture book is like a small theater."

"To live is the rarest thing in the world. Most people exist, that is all."

I never know what I think about something until I read what I've written on it.

学习数学的唯一方法就是做数学。

成功的唯一途径是拥有一个非常非常好的产品。