For the most part, the tales in this Cycle are preserved in eloquent verse and prose in 11th century manuscripts and this cycle has probably become the most popular of the four. It takes place under the reign of Cormaic mac Airt, High King of Tara whose presence looms large in the cycle of Kings, and revolves around the enigmatic warrior seer Finn Mac Cumhal and his troop of warriors the Fianna.
The lore of Finn is indigenous to Leinster, especially with regard to Leinster claims to the Boyne Valley and high kingship. Being a warrior God figure, he was adopted as a figurehead by many warring tribes in the area of Leinster during the late Iron age, tribes such as the Laighin, the Ui Gharrchon and the Ui Fhailghe [Ó‘hÓgáin]. He was adopted largely as an ancestor figure to inspire the Leinstermen to victory against the invading Ui Néill who were pressing hard into Leinster from their northern territories during the forth and fifth centuries.
It could be argued that Finn is probably the most famous figure from Irish mythology and the amount of literature we have concerning him is colossal. He had two hounds, Bran and Sceolan, who were said to be as tall as men and Finn himself is almost always linked inexplicably with hunting and in particular with the hunting of deer. In his youth he was known as 'Deimne' which is more than likely a corruption of Daimhne, meaning little stag [Ó hÓgáin], the name of his son 'Oisín' translates to little fawn, and the name of his grandson Oscar, the son of Oisín, translates as 'Lover of Deer'. The symbol of the deer is also prevalent in the legends surrounding Finn's lover and Oisín's mother 'Sadbh', which may translate as 'doe', who was put into the form of a deer by the druid Fear Dorcha.(in other sources his mother is given as Blaí Dearg).
Despite his hunting associations he is also a seer with divine wisdom and there are quite a few tales where we are told how Finn obtained this wisdom or "Imbas" (Imbas being an inspiration akin to enlightenment). The tale that most will be familiar with is the 'Salmon of Knowledge' where he puts his thumb upon a blister while cooking the Otherworld Salmon for Finegas (Finegas literally meaning "Finn the seer"), and after bursting the blister with his thumb, puts his thumb into his mouth to soothe the pain, thus being the first to taste of its flesh and attain the wisdom therein. Another tale where we see him acquiring this wisdom is in 'The Death of Cúldub' where, after spearing the otherworldly Cúldub, Finn catches his thumb in the door of a Sidhe mound when a woman of the Sidhe slams it shut to prevent Finn from entering. Again, he then pulls his thumb out from the door and puts it into his mouth to soothe the pain. In both cases the thumb is the mechanism for the transfer of wisdom, it is the thumb that comes into contact with the Salmon and the inside of the Sidhe Mound and we see him use this thumb of knowledge in many tales. One such example is in 'The Death of Lomna' where Finn finds a decapitated body and desires to know who the body belongs to. He puts his thumb into his mouth and by the help of the ancestral spirits of the dead it is revealed to him that it is the body of his fool Lomna.
Finns death is suspicious and his mysterious connection with the figure of Mongan provokes questions of reincarnation. Other significant figures from the Feninan cycle are characters such as Finn's grandson Oisín, who is lured away to the land of youth only to return hundreds of years later to find an Ireland alien to him. Upon his return to a newly christianised Ireland, he engages in a series of arguments with Patrick, reminiscing on the old glory days of the Fianna, and the arguments tend to view the pagan times as something of a golden age. This is notable in that it shows a christian literature whose pagan past seems to be still very much a recent memory. The earliest of the arguments preserved in manuscripts by Christian scribes have Oisín, unsurprisingly, being overcome by Patrick’s argument and Oisín is often portrayed as accepting Christ, an outcome that one would well expect to find in a mythology now under the control of a Christianising force in the country. However, as time went on the discourse between Oisín and Patrick was rewritten and redeveloped, the sense of awe and intimacy with the natural world, which is central to the pagan side of the argument, tends to come to the fore.
Other notable figures in the cycle are Finns loyal grandson Oscar, the great warrior Caoilte mac Ronan, and the hot headed Conan Mael. There is also Diarmuid and Gráinne, who upon betraying Finn are forced to flee, hiding from Finns rage in the barren and hidden places of Ireland in the great romance 'Toruigheacht Dhiarmada agus Ghráinne' The lovers wander for many years until the pursuit comes to a dramatic climax with the fulfilment of a prophecy and the death of Diarmuid.
Although at one time it was believed that Finn and the Fianna stories may have been historical however it is unanimously accepted now that this is untrue. However it is likely that there were indeed groups of roving warriors around whom such mythology grew up. These groups were probably a type of nomadic militia consisting of highly trained landless warriors acting as mercenaries for hire to various regional Kings as they travelled the country. The literature gives us ample description of what was required of a young warrior seeking to gain entry into the ranks of the Fianna. Despite being required to be versed in the art of poetry they were expected to perform a series physical feats as part of their initiation. These feats along with highly disciplined training may hint at some kind of native martial art or highly skilled warrior caste not unlike that of the Samurai of Japan. Examples of such physical tests include the initiate being expected to stand in a hole in the ground up to his waist, armed with nothing more than a hazel stick, an to fend off nine spears thrown by nine men (nine being a very significant number in Celtic tradition hinting at the ritual nature of such an initiation). Another requirement of the initiate was to run through a woodland while being pursued by warriors without breaking a twig beneath his feet and with such stealth so that the braids in his hair were not undone by the branches of the trees. Yet another was the young warrior being required to jump, while running at speed, over a branch as high as his head and under a branch as low as his knees.
In the literature, the Fianna consist primarily of two great families who were constantly hostile toward each other, Clan Baíscne of whom Finn was chief, and Clan Morna, who were lead by Goll Mac Morna. The inevitable explosions of this hostility along with a series of outside influences ultimately leads to the destruction of the Fianna, with the death-blow being dealt at the tragic battle of Gabhra. The language and the sentiment in Fenian Cycle portrays a time and an Ireland that sounds like those descriptions given by the Sidhe women of Magh Mell as they sought to lure mortals into the otherworld by relating it's beauties and delights. The vivid imagery in the Fenian literature and the ever-present sense of nostalgia seems to describe a time and a world that is richer than the world of the scribe during their transmission to manuscript. A pagan Ireland where the heroic Fianna rove through the beautiful landscape and the wild places of Ireland, sleeping under the stars, hunting and engaging in great adventures, repelling great armies, protecting the country from invasion and dealing with the people of the otherworld almost as much as those if the living world.
One of the most beautiful, prominent and distinct characteristics of this cycle is the awe and reverence for nature expressed by the verse. The Fenian Cycle represents a paganism that experiences the world and nature with animistic reverence and it is this distinctly Irish pagan characteristic that so deeply affected early Christianity. The memory of this pagan golden age lingers long in the national consciousness and an example from the relatively late 'Blackbird of Derrycairn' illustrates this well:
When Finn and the Fianna lived,
they loved the hills and not the hermit cells,
blackbird speech is what they loved,
not the sound, unlovely, of your bells.

© 2007 Seanchán Mac Conraoi