The story of Flonn's "thumb of knowledge" belongs in some versions to this period. To learn the art of poetry he went to Finnéces, who for seven years sought to capture a salmon which would impart supernatural knowledge to him —the "salmon of knowledge" —and after he had caught it, he bade Fionn cook it, forbidding him to taste it. When Finnéces inquired whether he had eaten any of it, Fionn replied, "No, but my thumb I burned, and I put it into my mouth after that"; whereupon Finnéces gave him the name Fionn, since prophecy had announced that Fionn should eat the salmon. He ate it in fact, and ever after, on placing his thumb in his mouth, knowledge of things unknown came to him.17 This story, based on the universal idea that supernatural knowledge or acquaintance with the language of beasts comes from eating part of an animal, often a snake, is parallel to the story of Gwion's obtaining inspiration intended for Avagddu18 and to that of the Norse Sigurd, who, roasting the heart of the dragon Fafnir, intended for the dwarf, burned his finger, placed it in his mouth, and so obtained supernatural wisdom. In German tales the animal is a Haselzvurm, a snake found under a hazel, like the Celtic salmon which ate the nuts falling from the hazels of knowledge. As told of Fionn, the story is a folk-tale formula applied to him, but the conception ultimately rests upon the belief in beneficial results from the ritual eating of a sacred animal with knowledge superior to man's. Among American Indians, Maoris, Solomon Islanders, and others there are figured representations of a medicineman with a reptile whose tongue is attached to his own, and it is actually believed by the American Indians that the postulant magician catches a mysterious otter, takes its tongue, and hangs it round his neck in a bag, after which he understands the language of all creatures.19
When Fionn sought supernatural knowledge, he chewed his thumb or laid it on his tooth, to which it had given this clairvoyant gift; or, again, the knowledge is already in his
