世界是平的，而我们正站在上面。

The Liskov Substitution Principle is a fundamental concept in object-oriented programming, stating that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program.

I think the most important thing in life is to be true to yourself.

There is no friend as loyal as a book.

Life is just a series of trying to make up your mind.

"The truth is often hidden in the details."