数算练习告诉我们算术运算的原理，而不是单单的记忆和不断演算。

The dead are never far from us. They’re in our hearts and on our minds and in the end all that separates us from them is a single breath, one last puff of air.

Philosophy is the discipline that forces us to confront the questions we would most like to avoid.

你的时间有限，所以不要浪费它去过别人的生活。