What's a "folk-motif"? Think of all the repeating significant figures and actions that populate folk tales, ballads, medieval romances, etc. They''re drawn from a vast vocabulary of like motifs which would be known to the audiences of the surviving tales, and they also suggest other possibilities known to the authors which were rejected in favor of the version presently before us. Wondering where you've seen that rudderless boat or magical duck or talking deer before? Try looking it up in this:
Thompson, Stith. Motif-index of folk-literature; a classification of narrative elements in folktales, ballads, myths, fables, mediaeval romances, exempla, fabliaux, jest-books, and local legends. Rev. and enl. ed.. Bloomington, Indiana University Press [1955-58].
Reference 398 R47 1955 v.1; Reference 398 R47 1955 v.2; Reference 398 R47 1955 v.3; Reference 398 R47 1955 v.4; Reference 398 R47 1955 v.5