Space and Time
Beauty and the Beast is a story about love and redemption and fits perfectly into Christian mythology. For agnostics though, in the absence of religious belief, the great metaphors of space and time are all that's left. But that's actually quite a lot really.
In the sciences, “double helix” and “string theory” and "black holes" may only be metaphors but they grab the imagination of writers, artists and musicians too. I like these lines by Vladimir Nabokov: “in the spiral unwinding of things, space warps into something akin to time, and time, in its turn, warps into something akin to thoughts…” (Speak, Memory, chapter 15).
In the arts, it's the same metaphors. I like these lines by W.H. Auden in In Memory of W.B. Yeats:
But for him it was his last afternoon as himself,
An afternoon of nurses and rumours;
The provinces of his body revolted,
The squares of his mind were empty,
Silence invaded the suburbs,
The current of his feeling failed; he became his admirers.
In other words, to quote Friedrich Nietzsche: Time, space, and causality are only metaphors of knowledge, with which we explain things to ourselves.
For another agnostic explanation, try this one.