No man, for any considerable period, can wear one face to himself and another to the multitude, without finally getting bewildered as to which may be the true.

在儿童时期没有养成思想的习惯。将使他从此以后一生都没有思想的能力。

数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。