The most necessary, the most important, the principal, the most essential thing for a musician is this: to know what he wants, what he can do, and what he ought to do.

译文：先从忧患方面考虑事情的人，就会享受到乐事，一时的操劳辛苦是永远安逸的开始。赏析：我们做事要有忧患意识，要有先苦后甜的意识，如果只图安逸快乐，就是祸患的开始。

孔子说：“君子不能象器皿一样，只有一种用途。”

Human beings, viewed as behaving systems, are quite simple. The apparent complexity of our behavior over time is largely a reflection of the complexity of the environment in which we find ourselves.

Everything is hard before it is easy. The day before something is a breakthrough， it’s a stupid idea.