The Dyad — Pythagorean Duality

The Aoristos Dyas (Indefinite Dyad) is the second principle in Pythagorean metaphysics — the arche of multiplicity, otherness, and the unlimited (apeiron). As Aristotle reports in the Metaphysics (987b), the Pythagoreans and Plato alike held that the Dyad was the material principle that receives the Monad's limiting action, and from their interplay all determinate number arises. Theon of Smyrna records that the Pythagoreans called the Dyad 'bold' (tolma) because it was the first to separate itself from the One. It stands on the 'unlimited' side of the Pythagorean Table of Opposites — aligned with plurality, femaleness, motion, and darkness.