καταβατέον οὖν ἐν μέρει ἑκάστῳ εἰς τὴν τῶν ἄλλων συνοίκησιν καὶ συνεθιστέον τὰ σκοτεινὰ θεάσασθαι.

So you have to descend in turn to the common dwelling of the others, and you have to get used to contemplating the darkness.

— Plato, Republic 7, 520c.