The challenge in theoretical computer science is not just to solve problems, but to understand the nature of problem-solving itself.
理论计算机科学中的挑战不仅仅是解决问题，而是理解问题解决的本质。
The truth is not always what we want to hear, but it is what we need to know.
解释：在人活动范围内的水就污浊，在野外无人地方的水就清洁。同为一样的水，都是从天边开源，有的混浊有的清洁，这是它们所处环境使它们这样的。