Free education is abundant, all over the Internet. It's the desire to learn that's scarce.

To understand mathematics is to speak the language of the universe.

数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。

意识是进化成功的工坊。

The task of the teacher is to lead the student from the known to the unknown.

每一栋建筑都是原型，没有两栋是完全相同的。