切记，对快乐感同身受虽然会增加世上的快乐，但对痛苦感同身受却无法消除痛苦。虽然如此让人更能忍受罪行，但罪恶不会因此消失。.
It must be remembered that while sympathy with joy intensifies the sum of joy in the world., sympathy with pain does not really diminish the amount of pain. It may make man better able to endure evil, but the evil remains.
The task of the teacher is to lead the student from the known to the unknown.
The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.
Innovation comes from solving real problems.
一个数学家的真正价值在于他们留下的问题。