Monad
In Pythagorean and Neoplatonic number theory, the One: the source the whole series of numbers comes out of, treated as its origin rather than as one number among the others.
Greek monas, “a unit”, from monos, “alone”.
In Pythagorean arithmetic the monad is not the number one so much as the origin of number: the point from which the counting series unfolds, and therefore not itself a member of the series it starts. Neoplatonism took the idea over and made it metaphysical. The One is the source everything flows out of, and it is described by what it is not, because every description would make it one thing among others.
The monad arrives in Christian theology by that route, and it does real argumentative work. Eustratius of Nicaea used it to place the Father as source at the apex of his triangle. The step to watch is the one from arithmetic to theology: what the monad rules out in a number series is not obviously what it rules out in God.
Where this comes up
Sources
- Eustratius of Nicaea, Sermon on the Holy Spirit, ed. Barmin 2006, quoted in B. Lourié, Scrinium 16 (2020), p. 353