As @f3nix, even I have caught a reminescence of Plato's Cavern, but it also happened I just listened (perhaps for the 100th time) to one of my favorite song: "Lateralus", by Tool. This song talks about the neverending trip of the human conscience to reach knowledge and self-awareness, both outside and inside ourselves, moving in "spirals" that become every round bigger. Your description of a inner voyage, almost a shaman's astral body trip, fits so well with the song!