The Pythagorean school's view is just the opposite of the Ionian school's. The latter thinks that the origin is single and changeable, while the Pythagorean school thinks that the number is the origin of the world, while the number is numerous and unchangeable for two reasons.

First of all, he believes that the essence of everything can be summed up in a number of regulations. Because the similarity between number and existence is more than water, fire and gas, that is, the stipulation of number is more common than physical attributes. So the number constitutes the model of the universe, and the phenomena of the world follow mathematical laws. The stipulation of mathematics includes three categories: first, the proportional relationship of mathematics, which determines the structure of things and the harmony between things; One is mathematical opposition, such as odd and even numbers; First, numbers represent the analogy between natural attributes and social attributes, such as 10 for perfection. Secondly, numbers exist before things, and people need numbers to know things. Numbers are the basic units of things, and the geometric structure corresponds to numbers: 1 is a point, 2 is a line, 3 is a surface, and 4 is a body. The process of the formation of the world: points produce lines, lines produce surfaces, and surfaces produce bodies, which produce four elements: water, fire, earth and air, which constitute sensible things.

Compared with the theory of material origin, the theory of number origin brings the concept of "form", which leads people to the level of speculation and pays attention to non-perceptual objects. Pythagoras' triple distinction of soul and his emphasis on mathematics had a great influence on Plato's idea and soul theory. But Aristotle criticized him for confusing abstract digital units with physical particles with volume, and thus put forward the absurd conclusion that numbers constitute sensible things.