Irish title translated as ‘The Adventure of the Great Fool’ or ‘The Lay of the Great Fool’; ScG Laoidh an Amadain Mhòir. An Irish and Scottish Gaelic folk-tale usually thought to be part of the Fenian canon, although Fenian names do not figure prominently in it. The name ‘Great Fool’ is given to the Perceval-like hero by an adversary in combat; he bears it ironically.
The ‘fool’ of the title is the dispossessed son of a great king. In Irish versions, he may be the son of the king of Munster, driven to the woods with his mother by an invading king of Leinster, who slaughters the hero's father and other members of the royal household. While in the woods, the hero and his mother grow much hair on their bodies, like wild beasts. The boy grows only at night but, when he does, reaches the height of a giant. On behalf of his impoverished mother, he seizes turf, flour, and sheep from neighbours. Hearing of his power, the king, residing in the captured castle, sends the hero on two apparently dangerous quests; but the hero first tames a wild dog, making him a pet, and then slays a wild boar, taking his carcass for food. The hero then wins the king's beautiful daughter, sometimes known as Eilín Óg, but subsequently murders the other members of her family when he learns what they have done to his; she remains his faithful wife.
When the hero magically loses his shins in a dark glen, he can still run faster than other men on his stumps. Not incapacitated, he spears a swift white deer and captures a white dog running with it. But implored by his wife, he turns over the deer and the dog to a hunter named Gruagach of the Castle of Gold, who claims them; this magnanimity wins an invitation to the castle for the hero and his wife. En route they encounter a champion named Maragach, who expresses his desire for the hero's wife. When Maragach learns that the hero will defend his wife's honour with nothing but his fists, he calls him a ‘Great Fool’ [Amadán Mór]. The Great Fool seizes Maragach's weapon and decapitates him. His legs are restored. Gruagach is later revealed to be the hero's brother. Together they successfully battle four giants.
Texts survive in Irish and Scottish Gaelic versions. See Transactions of the Ossianic Society, ed. John Daly, iv (Dublin, 1859); J. F. Campbell, Popular Tales of the West Highlands, iii (London, 1893); Jeremiah Curtin, Hero Tales of Ireland (London and Boston, 1894). Several commentators see links between this story and the development of the Arthurian hero Perceval: See L. Muehlhausen, ‘Neue Beiträge zum Perceval-Thema’, Zeitschrift für celtische Philologie, 27 (1927), 1–30; Sheila J. McHugh, ‘Sir Perceyvelle’: Its Irish Connections (Ann Arbor, Mich., 1946).