Pythagoras founded a philosophical and religious school in Croto where he developed the Pythagorean society, whose beliefs included that reality is mathematical in nature. The document presents a proof of the Pythagorean theorem using right triangles to demonstrate Pythagoras' innocence and the validity of his mathematical work. Constructing additional triangles around the original right triangle shows that the sums of the squares of the sides of two smaller triangles equal the square of the hypotenuse of the larger triangle.