你越深入数学，就越意识到还有多少未知。

"The very least you can do in your life is to figure out what you hope for. And the most you can do is live inside that hope. Not admire it from a distance but live right in it, under its roof."

——从浙江观潮返上海后题词，1916年9月15日

唯一真正的监狱是恐惧，唯一真正的自由是从恐惧中解脱。