Descartes’ classic sayings are as follows:

1. I think, therefore I am.

2. I am often lost in doubt. Fortunately, my thoughts finally made me discover "I am real."

3. The more you study, the more you discover your ignorance.

4. Reading outstanding books is like having a conversation with the most outstanding figures of the past.

5. The world is big, but the most equitable distribution is common sense.

6. When feelings only persuade us to do something that can slow down the process, we should restrain ourselves from making any immediate decisions and use other thoughts to stabilize ourselves until time and rest make the blood flow more stable. Emotions completely settled.

7. To be honest, people without knowledge always like to talk about the ignorance of others, but people with rich knowledge always discover their own ignorance.

8. It is not enough to have excellent intelligence. The main problem is how to use it well.

9. Will, understanding, imagination, and all functions of feeling all come from thinking.

10. People who are unable to make decisions either have too much desire or lack of awareness.

11. Conquer yourself, not the whole world.

12. Reading any good book is like talking to the best people in the world.

13. My efforts in studying have not gained any other benefits, but I am becoming more and more aware of my ignorance.

14. People who behave very pedantically, as long as they start by following the right path, can be much further ahead than those who leave the wrong path and run away.

15. Supportive opinions are helpful to me in two ways. On the one hand, they make me realize my mistakes. On the other hand, they are seen by a few people and are more clear than what one person sees.