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.

别人为食而生存，我为生存而食。

Only when one plunges into the powerful current of the times will one's life shine brilliantly.

Do not be avaricious； do not be a recluse.

The most necessary, the most important, the principal, the most essential thing for a musician is this: to know what he wants, what he can do, and what he ought to do.

你看到了，但你没有观察到。

Perhaps unhappiness can stem from having only one perspective to play with.