抽象的目的不是模糊，而是创建一个新的语义层次，在这个层次上可以绝对精确。
The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.
The most sustainable quarry is the one that balances production with environmental stewardship.
投资于农民教育就是投资于乳制品的未来。
The greatest wisdom is to recognize one's own ignorance.