When every penny must be calculated, the margin for error evaporates.

"Tennis is a mental game. Everyone is fit, everyone hits great forehands and backhands."

That is what learning is. You suddenly understand something you've understood all your life, but in a new way.

What can be shown, cannot be said.

The greatest gift you can give someone is your time.

孔子说：“不怕没人了解自己，就怕自己没有能力。”