While transcribing the lyrics from
Justus, I also noticed that the lines "And I seem to remember something that I heard / Of a fire and a cave and shadows on the wall" in "It's My Life" seem to be an allusion to Plato's allegory of the cave. I haven't read
The Republic yet, but I referenced the index of my copy and found that the allegory of the cave is at the beginning of Book Seven.