>[!abstract] >The tetractys is a triangular figure consisting of ten points arranged in four rows: one, two, three, and four points in each row, which is the geometrical representation of the fourth triangular number. As a mystical symbol, it was very important to the secret worship of [[Pythagoreanism]]. There were four seasons, and the number was also associated with planetary motions and music (Wikipedia, 2025). >[!related] >- **North** (upstream): — >- **West** (similar): — >- **East** (different): — >- **South** (downstream): —