The Tetractys is a triangular figure consisting of ten points arranged in four rows: one, two, three, and four points in each row. As a mystical symbol, it was very important to the followers of the secret worship of the Pythagoreans. Pythagorean symbol The Tetractys symbolized the four elements — earth, air, fire, and water. The first four numbers also symbolized the harmony of the spheres and the Cosmos. The four rows added up to ten, which was unity of a higher order (in decimal).… (More on Tetraktys)