Mathematics is not a deductive science—that's a cliché. When you try to prove a theorem, you don't just list the hypotheses and then start to reason. What you do is trial and error, experimentation, guesswork.

Leadership is about making the tough decisions when no one else is willing to.

The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

The only thing that makes life possible is permanent, intolerable uncertainty; not knowing what comes next.

今天我们种下的每一棵树都是留给后代的遗产。