Contents: Episode of the Thumb of Knowledge in Irish Tradition before the 10th Century; Thumb of Knowledge in Irish and Scottish Tradition after the 10th Century; Imbas Forosna, Teinm Laida and Dichetal do Chennaib; Taliesin and the Tradition of the Thumb of Knowledge; Story of Fearachur Leigh and the White Snake; Norse Sigurd and the Tradition of the Thumb of Knowledge; Finn mac Cumaill and the Tradition of the Thumb of Knowledge.