Tetractys
The Pythagorean figure of ten dots arranged in four rows — 1 + 2 + 3 + 4 = 10 — taken as the emblem of completeness. It is worth knowing because it cuts against a popular argument: in the tradition that produced it, the completion-numbers are four and ten, not three.
Four rows of dots — one, then two, then three, then four — summing to ten. The Pythagoreans swore oaths by it. It stands for the idea that the world's structure is generated out of the first four numbers and completed at ten.
The reason it appears on Debby is a correction. A popular argument holds that numbers past three are only repetition, adding no new principle, and credits the idea to Neoplatonic number theory. The handbook that theory comes down in, the pseudo-Iamblichean *Theologumena arithmeticae*, is organised as ten distinct principles with ten distinct profiles — and the figures it treats as completions are the tetractys and the decad. The tradition being cited says close to the opposite of what it is cited for.
Where this comes up
Sources
- Pseudo-Iamblichus, Theologumena arithmeticae; Debby research packet OTC-002