Plato 2: Opposites Generating Opposites

dubdobdee asked on yesterday's thread:

isn't the "form of largeness" another way of saying "the idea of size"*

*ie there wouldn't be a separate "form of largeness" and "form of smallness" -- "largeness" is (in this particular context) a synonym for size or scale?

No. Unless I'm misunderstanding, Plato is saying that there is a separate form of largeness, separate from smallness - which I think he'd have to say if he wants beauty to be a form in itself separate from ugliness, duality separate from unity, and so forth.

BUT there's a wrinkle! Earlier on in the very same dialogue, the Phaedo, Socrates says something that I would not have expected. The question is whether the soul can exist when the body is dead.

"Now," said he, "if you wish to find this out easily, do not consider the question with regard to men only, but with regard to all animals and plants, and, in short, to all things which may be said to have birth. Let us see with regard to all of these, whether it is true that they are all born or generated only from their opposites, in case they have opposites, as for instance, the noble is the opposite of the disgraceful, the just of the unjust, and there are countless other similar pairs. Let us consider the question whether it is inevitable that everything which has an opposite be generated from its opposite and it only. For instance, when anything becomes greater it must inevitably have been smaller and then have become greater."

( But wait, doesn't this contradict everything of Plato's I quoted yesterday? )