Tolkien used the image of the Cauldron of Story: myths, fairy tales, legends, names, images, and motifs stirred together across time, continually recombining into new tales.
This explains why all great stories echo one another without being mere copies.
They arise from the same deep cauldron of mythic imagination.
The centuries and millenia long process of Tradition, stories, myths, transmission,….
The Old Bones in the Soup
Tolkien compares stories to a pot of soup into which many old bones have gone.
The old myths nourish later tales even when their original forms are no longer visible.
This belongs to the idea that all stories are echoes, shards, or refractions of the primordial Story.