Unexplainable.

Fairy tales challenge the reader to imagine magical worlds different from our own. We are reminded by the fairy tale of the thing we never should have forgotten — that our world might have been different and is magical the way it is: unexplainable, unpredictable, wild, and surprising. With our imaginations awakened, we can see with new eyes our own world filled with wonder once again.

Abigail provides further Chesterton insight here.

Here she wanders about with Silas ...