The essence of mathematics lies in its freedom.
数学的本质在于它的自由。
社会系统是个人与个人之间、群体与群体之间关系的网络。
每一座建筑都是一个原型。没有两座是相同的。
The most profound ideas in mathematics often come from asking the simplest questions.
The past is a foreign country, but we are all its citizens.