It's all in Plato, bless me, all in Plato
Me: "And there was a man called Plato who told a story about a cave. You could sit in the cave and watch what the people next door were doing, but all you could ever see was shadows of them. And you had to guess what they were doing. Were they dancing, or eating, or sleeping, or jumping up and down? You had to tell from their shadows."
Niece: "Yes. Well. *I'm* going on holiday to that cave soon."
Me: "You're going on holiday to Plato's cave? COOL!"