One day, in Brayda, he saw many people staring at a Dutch math problem on the wall. Descartes asked a man next to him to translate it into Latin. The man didn't believe that the young officer could solve such a difficult problem, so he translated the problem sarcastically. Unexpectedly, two days later, Descartes gave the correct answer, which surprised the man. It turned out that he was the famous scholar Beckman at that time. Later, due to their common interests, they became best friends. He had a great influence on Descartes. Descartes once said that Beckman aroused his interest in science and "brought a mind that had left science back to the most normal and beautiful road." Descartes often studied mathematics day and night. One day, lying in his hospital bed, he looked up at the ceiling and lost in thought. He saw a spider busy weaving a web in the corner. It climbed up and down on the white ceiling for a while, and then climbed up and down along the spider silk. This wonderful acrobatics firmly attracted Descartes. Descartes was inspired by this. He thought, "Isn't this spider hanging in mid-air just a moving point? Can you use the intersection of two walls and the intersection of the wall and the ceiling to determine its spatial position? " He drew three perpendicular straight lines on the paper to represent the intersection of two walls and the intersection between the wall and the ceiling, and pointed out a point P in space to represent spiders. The distance from P to two walls is denoted by X and Y respectively, and the distance from P to the ceiling is denoted by Z.. In this way, as long as x, y and z have accurate values, the position of point P can be completely determined. In his view, the two walls and the ceiling meet in three lines, all of which meet in the corner. If the angle is taken as the starting point of calculation and these three mutually perpendicular lines are taken as three numbered axes, a coordinate system is formed. Any point in space can be represented by three ordered numbers on three numbered axes, and a group of three ordered numbers can also be represented by a point in space. In this way, number and shape have established an inevitable connection. Descartes continued his in-depth research and soon founded a new branch of mathematics-analytic geometry.