To be out of the cave and to see the sun for the first time is to see the world under the light of the sun for the first time, and is to see a greater world of which the other is now known to have been just a tiny misunderstood part. So you know that you are out of the cave because you now understand how those shadows you took for reality were produced, and there is no way you can ever believe in them again. If you go back into the cave and try to convince others to slip free of their shackles and come outside with you you will have your work cut out for you and you will perhaps be spared a further doubt. But now that you understand how the reality one world can be destroyed by the experience, inconceivable wholly within the terms of that world, of a second world - or it may be of the same world but now more amply perceived - the reality in that more ample perception will be subject to the doubt inherent in the possibility of yet a third world, a world corresponding to a still more encompassing perception. Once you've taken in the idea that a world, which in every way seemed a complete cosmos, can be transcended then how can you ever trust any world ever again? You will understand the principle of parsimony by which those who apprehend themselves to be the inhabitants of a certain cosmos dismiss all talk of a further cosmos, how they can prove with iron logic that the very notion of a further cosmos is incoherent, a result of the misuse of language, of language 'going on holiday'. If for Plato the philosopher is the one arguing for transcendence, today the philosopher is exactly the opposite, the one who argues against the possibility of any such transcendence. On the other hand you could maintain that this parable of transcendence is a generalisation from something that happens often in life; we are continually breaking through shells and thinking we have finally arrived, only to find a little further down the track that the boundaries of this new world are starting to crack. Or we might emerge into what seems a new world only to find that we have been here before and the old breach is still open, we just had our backs towards it. Either way it seems as if the only transcendence worth going for is with respect to all worlds, to the very principle of worlds. But how could you ever know you had arrived at such a non-place? If you have to ask, then you can't be there! But if you don't ask that doesn't entail that you are.