The world is full of signs and wonders that come, and go, and if you are lucky you might catch the tail of one as it flies past.

I used to think the world was broken down by tribes. Then I thought it was broken down by rich and poor. Then I thought it was broken down by stupid and smart. But I know now that it is broken down by people who are alive and people who are dead.

在数学中，提出问题的艺术必须比解决问题更有价值。