Psychology is a science, and teaching is an art; and sciences never generate arts directly out of themselves.

煤炭的真实成本必须既考虑其即时价值，也考虑其对社区和生态系统的长期影响。

The Langlands program is a vision of how mathematics could be unified.

"Sometimes, you have to look back in order to understand the things that lie ahead."

变得更好的唯一方式是与最强者竞争。