Place in the books
Bism matters because it reveals that Underland is not the bottom of things. Lewis gives one more depth below the witch’s kingdom, and that lower place is not drearier. It is fuller, hotter, and more alive. That reversal matters. The deeper world is not less real. It is more real.
The idea of Bism also sharpens the moral contrast in The Silver Chair. The Lady of the Green Kirtle wants to sink the children into illusion and confinement, while the language around Bism opens outward into delight, appetite, and freedom. Even when readers only glimpse it, the place enlarges the whole book.
Why the location matters
Bism is one of those Lewis inventions that feels larger than its page count. It hints that Narnia’s world keeps going beyond what the main characters have seen. That gives the setting depth and leaves readers with the sense that creation is richer than the witch’s prison-mind can imagine.