Tetractys

About the Tetractys
The duple progression (1 2 4 8) represents "the evolution of the vehicle" proceeding out of Unity, that is, the differentiation and division that constitute the physical body. The triple progression (1 3 9 27), in the order of involution (27 9 3 1), represents "the development of consciousness" as a return to unity.
www.cs.utk.edu/~mclennan/BA/PT/D-moretet.html

Tetractys - wikipedia.org
The Tetractys is an equilateral triangle formed from the sequence of the first ten numbers aligned in four rows. It is both a mathematical idea and a metaphysical symbol that embraces within itself, in seedlike form, the principles of the natural world, the harmony of the cosmos, the ascent to the divine, and the mysteries of the divine realm.
en.wikipedia.org/wiki/Tetractys

The Irrationals
Before the Secret Brotherhood was disbanded, its members really thought they had grasped the key to the cosmos.
www.anselm.edu/homepage/dbanach/pyth3.htm