Note 237 — Chapter II · SCIENCE AND RELIGION
Reading edition
For these see Theon, Expositio, pp. 93 sqq. Hiller. The τετρακτύς used by Plato in the Timaeus is the second described by Theon (Exp. p. 94, 10 sqq.). It is no doubt Pythagorean, but hardly as old as Pythagoras.