Taylor - Theoretic Arithmetic.pdf - Platonic Philosophy

And so of the rest, which abundantly proves that the monad
is causally every number.
CHAPTER XIV
On the properties of the duad, and triad.
THE duad, as it is beautifully observed by Proclus in his
Commentaries on Euclid, is the medium between the monad
and number. For unity, says he, by addition produces more
than by multiplication; but number, on the contrary, is more
increased by multiplication than by addition; and the duad,
whether multiplied into, or added to itself, produces an equal
quantity. Hence some of the ancients derive its appellation
from 701~ Buyat, because number begins from hence to enter into
multitude. Hence too, it was called Rhea, which signifies a
certain flux, because from hence the streams, i.e. the progressions
of multitude are derived. Again, the duad, as Martianus
Capella observes, is the mother of the elements; for 4 is the
offspring of 2. And it is also the first form of the even number.
The hebdomad likewise 64 which is both a square and a
cube, is produced by a continued multiplication by 2 from unity,
as we shall show when we discuss the properties of the
number 7. As Theo of Smyrna also observes,' matter, every
sensible nature, generation, motion, increase, composition, association
and relation, subsist according to the duad. And lastly,
as is evident from the preceding chapter, if 2 is multiplied
by any triangular gnomon, and unity is added to the product,
the sum will always be the gnomon of a square.
Again, from the junction of the duad with the monad the
triad is generated, which says Theo of Smyrna, is the first
number that has a beginning, middle and end. He adds,
* Mathemat. p. 156.