Buile Shuibhne (Irish pronunciation: [ˈbˠɪlʲə ˈhɪvʲnʲə], The Madness of Suibhne or Suibhne's Frenzy) is the tale of Suibhne (frequently anglicised as Sweeney or Sweeny), a legendary king of Dál nAraidi in Ulster in Ireland. The story is told in mixture of poetry and prose and exists in manuscripts dating from 1671–1674 but which was almost surely written and circulated in its modern form sometime in the thirteenth to fifteenth centuries. It is likely, from references in works going back to the tenth century, that some form of the tale of the mad king goes back to the first millennium.
King Suibhne: Suibhne was the pagan king of Dál nAraidi in Ireland. The son of Colman, Suibhne was married to Eorann. In the story he is depicted as an unruly man with a terrible temper. It is his temper and the resulting consequences of his actions that causes Saint Ronan Finn to curse him. Near the end of the tale Suibhne finds spiritual salvation when he is taken in from the wilderness by Bishop Moling. On his deathbed, Suibhne is given the sacrament having become a Christian, the curse of Bishop Ronan having run its course. 
The sound of a bell
In the legend, while St. Ronan marks the boundaries for a church, Suibhne hears the sound of his bell. When Suibhne learns that there will be a church established on his grounds, he is immediately angry and wishes to let St. Ronan know and expel him from the territory. His wife Eorann tries to keep him from leaving and grabs his cloak. He keeps on pulling, leaving his wife with the cloak and leaving himself to exit the house naked. When Suibhne arrives, St. Ronan is chanting the Office. This angers him enough to grab Ronan’s Psalter and throw it into the lake. As he drags the Saint, a messenger arrives to inform him of the Battle of Mag Rath (near modern Moira, 637 A.D.). Suibhne leaves with the messenger, leaving St. Ronan behind. The very next day, the Psalter is returned to the Saint unharmed, thanks to an otter from the Lake. The prior events lead the Saint to curse Suibhne to walk the world naked as he had the previous day . Prior to the battle, Bishop Ronan blesses the troops. Suibhne takes the sprinkling of holy water as a taunt and kills one of the bishop's psalmists with a spear and throws another spear at Ronan himself. The spear strikes Ronan's bell and breaks it. At this, Ronan curses Suibhne with madness. His curse is: 1) that as the sound of the bell had been broken, so now would any sharp sound send Suibhne into madness, 2) as Suibhne had killed one of Ronan's monks, so would Suibhne die at spear point. When the battle begins, Suibhne went insane. His weapons drop, and he begins to levitate like a bird. 
The effect of the curse
After being cursed, Suibhne is terrified by the battle and he drops his weapons with much fear inside. He flees in the way that a bird would, with his feet rarely touching the ground. He settles on a spot in a yew tree that is far from the battlefield. There he was discovered by his kinsman Aongus the Fat, who was fleeing from the battle. Then Suibhne fled to Tir Canaill where he was perched on a tree near a church. Then he fled through Ireland to Glenn Bolcain, wandered seven years, and then returned to Glenn Bolcain. There Suibhne saw his kinsman, Loingsechan, who fell asleep while searching for Suibhne. Suibhne then returned to his wife who was living with another man. Eorann said she would rather be with Suibhne, but he tells her to stay with the man. Suibhne then settles in a yew tree at Ros Ercain. Loingsechan eventually finds Suibhne here and coaxes him out of the tree only after lying to him and saying that his entire family had died. Loingsechan tries to recuperate Suibhne but, while recuperating, a mill hag taunted him into a contest of leaping. As Suibhne leapt along after the hag, he again took flight and returned to madness. Suibhne visits Eorann again but refuses to go in the house for fear of confinement. Eorann then tells him to leave and never return. Eventually, after travels throughout Ireland and Western England, Suibhne was harboured by Bishop Moling. He lived, broken and old, with the bishop, and the bishop entrusted his care to a parish woman. Unfortunately, that woman's husband, a herder, grew jealous and killed Suibhne with a spear. On his death, Suibhne received the sacrament and died in reconciliation.
Suibhne Meets His Fate
“Fly through the air like the shaft of his spear and that he might die of a spear cast like the cleric whom he had slain.”
The final stage of the curse acts itself out when Suibhne comes across a monastery that is run by St. Mo Ling. The Saint hears the mad man's story and has his cook feed Suibhne by creating a hole in the ground and filling it with milk. The cooks husband grows jealous of all the attention towards the madman and while Suihbne's drinks from the hole, he takes a spear and thrusts it into Suibhne, thus dying as St. Rónán had declared.
The poetry in the story of Suibhne is rich and accomplished, and the story itself of the mad and exiled king who composes verse as he travels has held the imagination of poets through to the twentieth century. At every stop in his flight, Suibhne pauses to give a poem on the location and his plight, and his descriptions of the countryside and nature, as well as his pathos, are central to the development of the text.
Many poets have invoked Sweeney—most notably T. S. Eliot and Seamus Heaney. Heaney published a translation of the work into English, which he entitled Sweeney Astray. The author Flann O'Brien incorporated much of the story of Buile Shuibhne into his comic novel At Swim-Two-Birds. Another version from the Irish text, titled The Poems of Sweeny, Peregrine, was published by the Irish poet Trevor Joyce. Sweeney also appears as a character in Neil Gaiman's novel, American Gods. A contemporary version of the legend by poet Patricia Monaghan explores Sweeney as an archetype of the warrior suffering from "Soldier's Heart".
Irish poet and playwright Paula Meehan loosely based her 1997 drama Mrs Sweeney on the Sweeney legend. Set in an inner-city Dublin flat complex called The Maria Goretti Mansions (a metaphor for the notorious Fatima Mansions Flats in Dublin), the play examines what life must have been like for Sweeney's wife; as Meehan states 'I wondered what it must have been like to be his woman.'. The play charts the trials and tribulations of Lil Sweeney's life in the Maria Goretti flats as she deals with crime, poverty, unemployment, drug abuse, and tries to come to terms with the pre-mature death of her daughter Chrisse, a heroin addict who died a year before the action starts from an AIDS related illness. Lil's husband, Sweeney, is a pigeon fancier who, upon discovering that all his pigeons have been killed, retreats into a bird-like state.
- Cycle of the Kings, wider grouping of contemporary narratives
- Magheralin, present-day village at the site of the church of Ronan Finn
- English translation by J. G. O'Keeffe, 1910, at CELT
- Dillon, Myles, Early Irish Literature, The University of Chicago Press, Chicago, 1972. pp 94-100
- Dillon, Myles. "Buile Shuibni." Early Irish Literature. Chicago: Univ. of Chicago, 1948
- Dillon, Myles. Early Irish Literature. pp. 98–100.
- Trevor Joyce. "The Poems of Sweeny, Peregrine". Retrieved 17 November 2011.
- Mad Sweeney
- Heart's Needle
- Meehan, Paula, Author's Note for 'Mrs Sweeny', in "Rough Magic: First Plays", Dublin: New Island Books, 1998, p. 463