"The world is full of obvious things which nobody by any chance ever observes."

Sustainability isn't a buzzword; it's a business imperative.

To be free is not merely to cast off one's chains, but to live in a way that respects and enhances the freedom of others.

悲观的人虽生犹死，乐观的人永生不老。

对天资在中等程度以上的人，可以和他谈论高深的学问；而对于中等以下天资的人，则不可以和他谈论高深的学问。