After the death of Cumhail mac Treanmhor, Muirinn took her newborn child away and gave him to two women, Bodhmall and Liath Luachra, who raised him in secrecy in the woods of Sliabh Bladhma (now Slieve Bloom in County Laois). They gave him the name Deimne, and trained him to run, leap, swim and hunt. One common story says they would often leave him in a field full of rabbits and charge him not to let a single one escape, or he would not eat that night. Deimne did some small amount of travelling and ranging about, and soon grew in size and skill until he could chase down deer, and did the hunting for himself and the two women, and it was well they ate in those days.

After a time, however, the two women told Deimne it was time for him to leave, for the sons of Morna were looking for him now in earnest. And so he did, and a faster runner or a stronger swimmer you'd be pressed to find. One day in his travels, he came upon a lake with a number of other young boys swimming in it. They called to him to come and join them, and so he did. They had a swimming contest, and Deimne beat them all soundly. One of the boys was said to remark that he was "fair of hair and fair of shape", and so they all called him Finn, meaning fair, and that is how he got his name.

Finn stopped next in Carraigh (now Kerry), where he entered into service with the king who his mother Muirinn had married after Cumhail died. This man was not the high king, simply a regional or tribal chief. Now Finn had a much sharper and cannier mind than most Fir Bolg, owing to his mother's ancestry, and one day entreated the king to play chess with him. After suffering several defeats at Finn's hand, the king asked him how it was that he played the game so well. Finn told the king some offhand lie or another, which the king saw through, and confronted him as Muirinn's son by Cumhail. When Finn conceded this, the king sent him forth for fear that Finn would be killed by Clan Morna while under his roof, which would bring great shame to him and his family.

Finn then went off in search for his father's brother Crimall in the province of Connacht, but on the way encountered an old woman crying tears of blood. When Finn asked her why she lamented, she told him that she and her only son had been beset upon by a huge warrior, and that the two were now fighting in a nearby glade. Finn rushed there and defeated the warrior in battle. Fastened about the warrior's neck was a bolg of crane-skin, which Finn took with him. He later found Crimall, now an old man and living in a lonely, secluded place with a handful of Fianna who hunted and cared for him. Upon seeing Finn walk through the door with the crane-skin bolg around his neck, Crimall cried that he was set upon by ghosts, and the Fianna there had to restrain him while Finn told his story. Crimall then followed with a story of his own, telling Finn that the warrior he slew was the man who dealt the first blow to his father at the battle of Cnucha, and that the bolg had originally been Cumhail's, and contained the treasures of Clan Baiscne. Seeing Finn appear with his father's bolg had convinced Crimall that he was Cumhail's ghost.

Crimall and his men inspired Finn to try and reclaim his father's place at the head of the Fianna, but any youth wishing to join them at that time had to pass a number of harrowing tests. He had to defend himself against the spears of nine men with only a shield and a hazel limb. He had to run through the woods of Ireland, the Fianna at his heels after him, and not disturb the plaiting of his hair, nor snap any twig under his foot, nor let the Fianna catch him, for they would beat him soundly. He had to jump over a branch as high as his head, and pull a thorn from his foot while running full speed. In addition to these physical tests, he had to recite twelve epic poems. Finn's physical prowess was undoubtable, but Crimall directed him to an old poet named Finneigas to learn the twelve poems.

Finneigas lived on the banks of the river Boyne, for the poets believed it was always at the brink of water that inspiration was bestowed upon them. And for all the years that he had lived there, Finneigas had been trying to catch a great fish called the salmon of knowledge. He had known a prophecy which said that a man with a fair name would catch the salmon, eat it, and have all the world's knowledge. So Finn, still calling himself Deimne, stayed with Finneigas learning the twelve poems. One day, Finn heard a great thrashing at the river. Rushing to the sound, he found Finneigas wrestling a massive salmon from the water. The effort had exhausted him, so he bade Finn to take the fish and cook it, but warned him not to eat any of it. Finn did as he was asked, but while roasting the fish, he saw a blister forming on its skin. Finn reached out and broke the blister with his thumb. In doing so, he burned himself and instinctively put his thumb in his mouth to cool it. Later, when he brought the cooked fish to Finneigas, the poet saw in the boy's eyes the knowledge he had spent so many years searching for. He asked Finn for his name, and Finn replied that it was Deimne. "Och, it is not, but it is Finn your name is," Finneigas said, "And yours is the fair name in the prophecy, and not mine." He then gave the rest of the salmon to Finn to eat, and from that day forth, whenever Finn had a question that needed answering, he put his thumb in his mouth and knew the answer. This is probably the most famous and well-known of all the tales of Finn's life.

Since there was nothing else that Finneigas could teach him, Finn left for Tara to fulfill his destiny. He arrived just in time for the great festival of Samhain (what is now Halloween). During this festival, there was a sacred law that no one begin a quarrel or act on an old grudge against another for the entire duration. This was just as well, for when Finn entered the great hall, the Ard Rig was seated at the feast table with Goll mac Morna and his brother, Conan Maol. Finn raised his voice above the crowd and proclaimed that he was the son of Cumhail, here to pledge his loyalty and service to the king. The king broke the ensuing silence by accepting Finn's pledge and seating him next to his own son.

During the feast, the high king rose and spoke of an evil spirit that had visited Tara every year during the festival. Accounts of this spirit's form vary - some stories portray it as a dragon or other great monster, while others see it as a prince of the Tuatha de Danaan. Either way, each year it would descend upon Tara, playing sweet music that lulled the inhabitants to sleep, then it would breathe fire that caused great damage to the city. The high king asked if there was any man brave and stalwart enough to keep Tara untouched by this creature from sunset until sunrise, promising whatever reward was deemed right for him to have. Silence filled the great hall, but at last Finn arose and promised that he would keep Tara safe.

That evening, as Finn strode around the walls of Tara, an old friend of his father's named Fiachra approached him, and made him a gift of a magical spear. He told Finn that the spear had never missed its target, and when the tip was pressed against his forehead, the music of the Sidhe would not affect him. Finn took the spear and, when the sun set and the spirit approached the city, he did as he was told and pressed the spear to his forehead. Although every man, woman and child in the city fell deeply asleep, Finn remained awake. And when the spirit beheld him unaffected, it turned and ran back towards its otherworldly lair, but Finn cast the spear and struck the spirit down. There he planted the spear in the ground, cut the head from the spirit, and impaled it upon the spear to stand there until sunrise.

When the sun rose and it was clear that Finn's promise had been fulfilled, the king took counsel with his brehons, or judges, to determine what reward was due Finn. It was agreed between them that he should be made Rigfennid, leader of all the Fianna. Goll mac Morna was given the chance to take Finn's hand and accept his leadership, or to leave Ireland forever. He took Finn's hand then and there, and the two made an oath to swear off vengeance forever. This oath became an integral part of the Fianna's code, and all the warriors gave their word that they would follow the example of Finn and Goll.

What followed is considered to be the golden age of the Fianna, and the height of their power and influence. Finn was well-liked by all of his men, and his women as well, and as much as he was loved during peace, he was feared during battle. Many are the stories told of the ensuing years of his leadership, his great deeds and battles won. In the next chapter, The Life of Finn mac Cumhail 3: Finn's Adulthood, I will try to briefly recount the most common and well-known of these tales. Or, go back to the previous chapter, The Life of Finn mac Cumhail 1: Preface if you haven't read it already.