Courtesy costs nothing. Lower the toilet seat after use. Let the people in the elevator exit before you enter. Return shopping carts to their designated areas. When you borrow something， return it better shape (filled up， cleaned) than when you got it.

If you don't fail at least 90 percent of the time, you're not aiming high enough.

晏子春秋

数学直觉就像肌肉一样 - 通过锻炼会变得更强大。

不要等待完美的时刻，抓住这一刻并让它变得完美。