很难想象有谁不曾一度因爱或因缺乏爱而萎靡不振。
The pursuit of mathematical truth is a noble endeavor.
The past is a shadow that follows us, but the future is a light that guides us.
经验的直接内容是我们唯一可以知道的现实。
数学的乐趣在于努力理解的过程。