Short story: Descartes, a French philosopher who lived in17th century, is generally regarded as the real inventor and founder of modern philosophy. Just like this, in Descartes' period, he was able to cut to the chase, put aside all theological dogmas, set out from the difficult thinking itself, and set out from such a very simple and clear proposition as "I think therefore I am", which had to make people feel refreshed and suddenly enlightened.

Why do you say "I think, therefore I am"? The so-called "I think" means that I am thinking and I am skeptical. That is to say, I have the ability of perceptual thinking, which is the most important sign that people are different from animals. Only by constantly thinking about nature can people become people. Only by constantly thinking can people become advanced. Only by constantly thinking can people adapt to this changing world. And people who have lost their thinking ability cannot improve and adapt to this world, how can they talk about "existence"?