追求数学真理就是追求美、优雅和简洁。
里氏替换原则是面向对象编程中的一个基本概念，它指出子类的对象应该能够替换超类的对象而不影响程序的正确性。
The most beautiful as well as the most ugly inclinations of man are not part of a fixed biologically given nature, but result from the social process which creates man.
Existence is not its own justification.
过去是一个异国；他们在那里的做法不同。