Everyone likes to bring up Plato's Cave. No one wants to talk about his light emission theory. Wonder why? Maybe because it shows what a crackpot you have to be to take the cave theory literally, as though you can "walk out".

Again, it is useful for therapeutic purposes (pretend x is true, then use that pretense to do something beneficial which you've hopefully checked with your logical brain to make sure it isn't stupid and insane.

It's also cool as a metaphor, because on some level, obviously you can influence your surroundings and make the world your oasis. It's just a matter of recognizing that this is a result of your actions, not your imaginative light being flowing from your mind.