数学不是一项观赏性运动；要理解它，必须积极参与其中。

In times of change, the learners inherit the earth while the learned find themselves beautifully equipped to deal with a world that no longer exists.

"The most profound discoveries often come from the simplest questions."

——在遗嘱上签名，稍休后说几句话勉励各同志，1925年3月11日