I set aside talking about Underland from Lewis's The Silver Chair because I felt that another piece of literature greatly enriches our understanding. The concept of this underworld (Planet Earth Cave edition anyone?) and its enchanted and stultified inhabitants finds is reminiscent of classical journeys to Hades in Dante, Spenser, Virgil, and Ovid, and a little bit of Verne's Journey to the Center of the Earth with descriptions of strange beasts and sights and untasted delights of Bism. The soporific underground sea of glass reminds me of Lethe. The most marked feature at this point in the story is in the character's separation from the reality of Overland, of their home. They find it difficult to remember (like Frodo) the joys of their Narnia and struggle remember and hold to (a constant theme of this book) the truth. The evil Witch plays upon this very danger and seeks to convince them that recollections of a world above are the products of childish imaginings. The sun is but a larger lamp, a lion but a larger cat.
Her objections strike to the bones and sinews of what fantasy is. Beyond the simple and profound solution of Puddleglum I'd like to now call in my other literary source, and perhaps Lewis's as well. George MacDonald's Photogen and Nycteris is a short, stand-alone fairy tale. The premise of the story revolves (literally and celestially) around two enchanged characters: Photogen, a boy who is born and kept constantly in the light of the sun, with no curiosity or knowledge of the night, and Nycteris, a girl who is likewise raised in the bowels of a cave with no knowledge of the day. The real insight into The Silver Chair stems from the wonder-filled paradigm shift of Nycteris. In the depths of her cave-room shines one dim, alabaster (thank you Mary Magdalene) lamp. The darkness of her life fills Nycteris with a love for her lamp, in a way that it hints at something beyond the darkness. It holds her whole attention and compassion. When it is snuffed out and broken by an earthquake, she seeks to follow it to where it has gone. Guided by a fire-fly, the ghost of her lamp, she finds her way into the outside world of the night. MacDonald's romantic language does beautiful justice to the childish wonder which quite realistically explores this fantastic situation. The full moon is to Nycteris the mother of all lamps. When it waxes and wanes it reenacts the death-glorification that was modeled by the lamp-to-fire-fly transformation.
This world-view considers the latent largeness inherent in all things. Very Platonic and also to be found in Lewis's The Last Battle. The special connection to the concept of Underland rests in the worth in seeking for beyondness, of seeing the metaphor in all things though through a glass dimly. It takes courage and childishness.