The great secret that all old people share is that you really haven't changed in seventy or eighty years. Your body changes, but you don't change at all. And that, of course, causes great confusion.

The truth is always revolutionary.

我宁愿活得好像有上帝，死后发现没有，也不愿活得好像没有，死后发现有。

计算效率的概念是学习算法设计的核心。