The real challenge in computer science is not to write programs, but to understand the nature of computation.

The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.

森林的真正价值不仅在于其木材，还在于其维持生命的能力。

The ideas of economists and political philosophers， both when they are right and when they are wrong， are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men， who believe themselves to be quite exempt from any intellectual influence， are usually the slaves of some defunct economist.