"The world is full of obvious things which nobody by any chance ever observes."

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

Lisp语言被设计成可扩展的，很容易为其添加新功能。

The six colors， including the white background， represent the colors of all the world's flags ... this is a true international emblem.

德性的知识，不是从见闻中产生的。