Definition:Tetractys
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Definition
The tetractys is a central concept in the mystical beliefs of the Pythagoreans.
It consists of $10$ points arranged in a triangle:
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.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $4$
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $10$
- 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {A}.2$: Pythagoras (ca. $\text {580}$ – $\text {500}$ B.C.)
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $4$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $10$
- 2008: Ian Stewart: Taming the Infinite ... (previous) ... (next): Chapter $2$: The Logic of Shape: Pythagoras