Finn Eces is a legendary Irish

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 poet and sage, according to the Fenian Cycle

Fenian Cycle

The Fenian Cycle , also referred to as the Ossianic Cycle after its narrator Oisín, is a body of prose and verse centering on the exploits of the mythical hero Fionn mac Cumhaill and his warriors the Fianna. It is one of the four major cycles of Irish mythology along with the Mythological Cycle,...

 of Irish mythology

Irish mythology

The mythology of pre-Christian Ireland did not entirely survive the conversion to Christianity, but much of it was preserved, shorn of its religious meanings, in medieval Irish literature, which represents the most extensive and best preserved of all the branch and the Historical Cycle. There are...

. He is the teacher of Fionn mac Cumhaill

Fionn mac Cumhaill

Fionn mac Cumhaill , known in English as Finn McCool, was a mythical hunter-warrior of Irish mythology, occurring also in the mythologies of Scotland and the Isle of Man...

, according to the tale The Boyhood Deeds of Fionn

The Boyhood Deeds of Fionn

The Boyhood Deeds of Fionn is a medieval Irish narrative belonging to the Fenian Cycle of Irish mythology. As its title implies, it recounts the boyhood exploits of Fionn mac Cumhaill, the cycle's central figure...

. For years he tries to catch the Salmon of Wisdom

Salmon of Wisdom

The Salmon of Knowledge is a creature figuring in the Fenian Cycle of Irish mythology. This salmon was sometimes called Fintan, or Finntan, in ancient times and is sometimes confused with Fintan mac Bóchra who was also known as, "The Wise" and once transformed into a salmon...

, a fish that will grant all the world's knowledge to whoever eats it. He is unsuccessful until he takes the young Fionn as his charge, but when Fionn cooks for him, he burns his thumb and puts it in his mouth. He therefore receives the fish's knowledge, which he can access by putting his thumb in his mouth again.

Nuada

Nuada

In Irish mythology, Nuada or Nuadu , known by the epithet Airgetlám , was the first king of the Tuatha Dé Danann. He is cognate with the Gaulish and British god Nodens...

 is referred to in some sources as Nuadu Finn-Éces, and certain authors suggest that the story of Fionn Mac Cumhall and the salmon of knowledge is related to the cult of Nodens

Nodens

Nodents is a Celtic deity associated with healing, the sea, hunting and dogs. He was worshipped in ancient Britain, most notably in a temple complex at Lydney Park in Gloucestershire, and possibly also in Gaul...

 or Nuada

Nuada

In Irish mythology, Nuada or Nuadu , known by the epithet Airgetlám , was the first king of the Tuatha Dé Danann. He is cognate with the Gaulish and British god Nodens...

, which was introduced into the Boyne Valley mythological corpus some time in the early centuries BC. Nuada was integrated into Fenian lore as an ancestor of Fionn, the name Finn-Ecas meaning "Finn the Seer."