数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。
Mathematics is not just about numbers, equations, computations, or algorithms: it is about understanding.
Well may the boldest fear and the wisest tremble when they contemplate the situation of our country.
Representation of the world, like the world itself, is the work of men; they describe it from their own point of view, which they confuse with the absolute truth.
心理现象只能通过它们对行动的后果来理解。
Every man has his secret sorrows which the world knows not; and often times we call a man cold when he is only sad.