That famous saying is Confucius’ thinking on learning and thinking

The Analects of Confucius·Politics is Second

Confucius said: Learning without thinking is a waste, thinking without thinking If you don’t learn, you will be in danger

Confucius said: If you study without thinking, you will be blinded by the appearance of knowledge; if you think without learning, you will be more dangerous because of doubts.

In addition, Confucius said: "I have not eaten all day long, stayed up all night, and thought, which is of no use. It is not as good as learning." That’s it.”