[During]
Precisely. Plato's allegory goes on to describe a man who is freed from the cave and learns about the world, and then returns to the cave to attempt to educate others, who may then kill him. [wry] Education isn't always wanted.
But the point is -- [spreading his hands] -- Plato's allegory describes someone who learns that what he'd understood as truth was actually a result of misperception. He didn't know enough to have a correct opinion on reality. And who's to say that once he left the cave and learned about the world outside it, he was correctly perceiving the real world? What if he was colorblind? What if he emerged in a jungle and assumed the whole world was jungle?
It is impossible to know, for certain, that we understand reality; there may always be something more to what we are able to experience. A true philosopher will question everything he sees.