There's an episode in Plato's writings (I'm not sure) which I can't find and I'd appreciate any help. Socrates (I'm not sure), advances a theory through a fable which is hard to believe. An interlocutor asks skeptically whether anybody would believe such nonsensical claim. The answer from Socrates is something along these lines: "not in this generation, no, but in 2 or 3 generations they will believe it."
Would you recall where this conversation is located???