Definition:Tetractys

Definition
The tetractys is a central concept in the mystical beliefs of the Pythagoreans.

It consists of $10$ points arranged in a triangle:


 * Tetractys.png

based on the notions that:
 * $1$ represents the point
 * $2$ represents the line
 * $3$ represents the surface
 * $4$ represents the solid
 * $1 + 2 + 3 + 4 = 10$

and therefore:
 * $10$ represents the universe.

Also known as
Some sources give this as tetraktys.