What are the motifs in The Hollow Hills by Mary Stewart?

Stories and rumors are recurring ideas in the story. At the center of the Merlin and Arthur myth are the wild stories and rumors that surround them. Merlin addresses these head-on in his narration and dialogue; according to the stories, Merlin came to Uther, cured him, and then flew away on a dragon. He was also said to have taken Arthur to a mysterious boat or island and held him there as a child. Another was that he disguised Arthur as a pack mule and brought him on his adventures.