Of course you are right, dear friend, in ascertening the stability of the eternal ideas. Thus truth has an eternal value for Platon.

But then we also have tis other truth. The one that is seen as shadows on the walls of some obscure locations. This is the kind of truth we need epistemology for.

Let me reformulate this again: Since we cannot see the eternal ideas by our senses, but must infer them from the effect they make on the world, how can we judge which parts of the shadows are important, and which are the artefacts of them being shadows?

Is this the parable of the hole (sorry I have no dictionnary at hand it is German Hoehle) in other words?

In my opinion this parable is a fundamental teaching of Platos epistemology: We can know some things, and we even can advance in knowledge, but we won't really find out about the prime things directly, and thus are unable to gasp, what I want to call for the time being, absolute truth.

Objections anybody?