过度捕捞就像透支信用卡，终将付出沉重的代价。
Overfishing is like maxing out a credit card - the heavy price will come due eventually.
The only limits that exist are the ones you place on yourself.
The best things in life are free.
That man, I think, has had a liberal education who has been so trained in youth that his body is the ready servant of his will.
教师之为教，不在全盘授予，而在相机诱导。
I think a lot about labor and time.
Mathematics is not about numbers, equations, computations, or algorithms: it is about understanding.