[Plato], first being acquainted from his youth with Cratylus and the opinions of the Heracliteans, that all perceptible things are always flowing and that there is no knowledge of them, later indeed held these very opinions himself.

And each time you must give an account of the hypothesis itself, you will do so in this fashion: you will posit a new hypothesis, choosing from the higher ones the one which seems to you to be the best, until you reach something sufficient. You will not muddle yourself up, as the controversialists do, by discussing the premiss and the conclusions that follow from it both at the same time, at least so long as you want to find something of the things that are. For this these characters have not one account nor one thought. For they think themselves sufficient as to wisdom by making a posset of everything together, to be able to please themselves. But you, if you would be a philosopher, will do, I think, as I say.