I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones。
数学的研究是所有智力和精神进步不可或缺的基础。
The most important challenge facing the world today is the need to create strong, effective, and accountable states in the developing world.
——〈在东京对同志的声言〉，1915年10月25日
Sometimes we get sad about things and we don’t like to tell other people that we are sad about them.
有时我们会为某些事情感到悲伤，而我们不愿意告诉别人我们为此感到悲伤。