The argument, when drawn out, is virtually this: if, because two subjects are coessential, a third is pre-supposed of which they partake, then, since either of these two is coessential with that of which both partake, a new third must be supposed in which it and the pre-existing substance partake and thus an infinite series of things coessential must be supposed. Vid. Basil. Ep. 52. n. 2. [Cf. Aristot. Frag. 183, p. 1509 b 23.]