The artist must be free, even from himself.
孔子说：“我十五岁立志于学习，三十岁有所建树，四十岁不困惑，五十理解自然规律，六十明辨是非，七十随心所欲，不违规。”
Mathematics is a creative endeavor, just like art or music.
译文：用钱财交朋友，钱财用完了交情就会断绝；贪美色面结合，到年老色衰时爱情就会消失。
Courage is the most important of all the virtues because without courage, you can't practice any other virtue consistently.