river Boyne and studied under him. Finnegas had spent seven years trying to catch the salmon that lived in Fec's Pool () of the Boyne, for it was prophesied the poet would eat this salmon, and "nothing would remain unknown to him". Although this salmon is not specifically called the "Salmon of Knowledge", etc., in the text, it is presumed to be so, i.e., the salmon that fed on the of knowledge at the well of Segais. Eventually the poet caught it, and told the boy to cook it for him. While he was cooking it, Demne burned his thumb, and instinctively put his thumb in his mouth. This imbued him with the salmon's wisdom, and when Éces saw that he had gained wisdom, he gave the youngster the whole salmon to eat, and gave Demne the new name, Fionn. Thereafter, whenever he recited the teinm láida with his thumb in his mouth, the knowledge he wished to gain was revealed to him. In subsequent events in his life, Finn was able to call on ability of the "Thumb of Knowledge", and Fionn then knew how to gain revenge against Goll. In the Acallam na Sénorach, the ability is referred to as "The Tooth of Wisdom" or "Tooth of Knowledge" (). Finn's acquisition of the Thumb of Knowledge has been likened to the Welsh Gwion Bach tasting the Cauldron of Knowledge, and Sigurðr Fáfnisbani tasting Fáfnir's heart. Fire-breather of the Tuatha de Danann One feat of Fionn performed at 10 years of age according to the Acallam na Senórach was to slay Áillen (or ), the fire-breathing man of the Tuatha Dé Danann, who had come to wreak destruction on the Irish capital of Tara every year on the festival of Samhain for the past 23 years, lulling the city's men to sleep with his music then burning down the city and its treasures. When the King of Ireland asked what men would guard Tara against Áillen's invasion, Fionn volunteered. Fionn obtained a special spear (the "Birga") from Fiacha mac Congha ("son of Conga"), which warded against the sleep-inducing music of Áillen's "dulcimer" () when it was unsheathed and the bare steel blade was touched against the forehead or some other part of the body. This Fiacha used to be one of Cumall's men, but was now serving the high-king. After Fionn defeated Áillen and saved Tara, his heritage was