Argument the Seventeenth.
The following axioms, which are Aristotelic, are by a much greater priority Platonic, viz. "Every thing which is generable, is also corruptible, and every thing unbegotten is incorruptible." For the former of these is mentioned by Plato in the Republic, and the latter in the Phædrus. In the Republic, therefore, Socrates, personating the Muses, says, "Since every thing which is generated is corruptible;" and [in the Phædrus) he says, since the soul is unbegotten, it is necessarily also incorruptible. For he spews that every principle is unbegotten, and because unbegotten, he demonstrates that it is also incorruptible. ‡ For these things being true, it is necessary that every thing which is corruptible should be generable; since, if it is unbegotten, the corruptible will be incorruptible, which is impossible. Every thing also which is incorruptible is unbegotten; for if generable, the incorruptible will be corruptible. These things, therefore, necessarily following, if the universe is incorruptible, it is also unbegotten; * as is evident from the above premises. For the Demiurgus, according to Plato, is the source of immortal natures; but the immortal is indestructible, as it is said in the Phædo. For scarcely will any thing else be indestructible, if the immortal is not a thing of this kind. ‡ And this, indeed, Cebes says, and Socrates grants. § If, therefore, every thing which was generated by the Demiurgus is indestructible, (for that which was generated by him is immortal, and this is indestructible,) it is also necessary that it should be unbegotten, through what we have demonstrated to be consequent to the two preceding axioms; one of which is, that every thing generable is corruptible; but the other, that every thing ingenerable is incorruptible. So that, not only according to Aristotle, but also according to Plato, it is demonstrated through these two axioms, that the world neither had a temporal generation, nor is corruptible. For if * that which is inordinate is unbegotten, but that which is arranged is incorruptible, that which is without arrangement will be more excellent than that which is arranged. For as the ingenerable is to the generable, so is the incorruptible to the corruptible; so that it will be alternately, as that which is ingenerable is to that which is incorruptible, so is that which is generable to that which is corruptible: and as that which is generable is to that which is corruptible, so is generation to corruption. If, therefore, generation is better than corruption, and the generable is essentially more excellent than the corruptible, the ingenerable also will be more excellent than the incorruptible. Hence, if that which is inordinate is ingenerable and corruptible, but that which is arranged is incorruptible and generable, that which is without arrangement [so far as it is ingenerable] will be more excellent than that which is arranged; and that which from the inordinate produces that which is arranged, will produce that which is less from that which is more excellent; in consequence of producing from that which is ingenerable and corruptible, that which is afterwards generable and incorruptible. One of these, therefore, will not be ingenerable and corruptible, but the other generable and incorruptible; or vice versa. But neither is the maker evil; so that what is arranged is not corruptible. And if that which is arranged is from that which is without arrangement, the unarranged is not incorruptible; since it is not, when that which is arranged has an existence. Or, if this is not admitted, each of these will be generable and corruptible. But whether that which is inordinate is generable, being generated from that which is arranged; or whether that which is arranged is corruptible, he who corrupts that which is well arranged, either did not properly harmonise it, and therefore is not good; or he corrupts that which is well harmonised, and is evil. All these consequences, however, are impossible. Hence, that which is inordinate is not prior to that which is orderly: and therefore it follows, that what is orderly is unbegotten, and in like manner that it is also incorruptible.