Ó Murchadha, Seán na Ráithíneach (1700–62), poet and scribe, was born in early March 1700 in Carrignavar, Co. Cork, son of farmer Diarmuid Ó Murchadha. His mother's name is unknown but according to Ó Donnchadha either his mother or grandmother was a descendent of Cearbhall Ó Dálaigh ‘na n-amhrán’ from Kilmurry. His grandfather, Domhnall Ó Murchadha, fought on the side of Viscount Muskerry (qv) against Cromwell (qv). His only brother, Domhnall, died when Seán was nineteen and the lament he composed for him, ‘Mo bhrón mo chumha’, is the earliest of his compositions extant. After his brother's death he took over the running of the farm. He learned English and Irish from the poet Seán Ó Macháin, schoolmaster to the Mac Cárthaigh Spáinneach family in Carrignavar. Ó Donnchadha notes that Ó Murchadha's manuscripts also display some knowledge of Latin. He learned to play the pipes, probably the uileann pipes, at an early age.
Three other figures from his local area played an important part in his education: the parish priest and poet, Fr Conchubhar Mac Cairteáin (d. 1737?), who gave him books and assisted him with his compositions; the Cork shopkeeper, Eoghan Mac Suibhne, who lent him books; and the poet, Liam an Dúna Mac Cairteáin (qv), who was in charge of the Blarney cúirt éigse (bardic court) and probably had the greatest influence on the young poet. Humorous verses were exchanged between them and in one instance Ó Murchadha claimed that Liam an Dúna had learned to write poetry from Ó Murchadha and not vice versa. In the lament he composed on Dúna's death in 1724, he emphasised the welcome people received in his home: ‘Níor dhúnta riamh do dhún, a Liam’ (‘Your door was never closed, Liam’). In 1737 he wrote an elegy on Fr Conchubhar Mac Cairteáin, (BL, Add. MS 31876). Breandán Ó Conchúir draws attention to Ó Murchadha's close friendship with members of the clergy and remarks that these priests, both within his own parish and in neighbouring parishes, were his mainstay throughout the course of his life.
Ó Murchadha was an important scribe and collector of manuscripts. At least sixteen of his manuscripts from the period 1719–62 are extant. These are to be found in the RIA, BL, NLI and the university libraries of Maynooth and Cork. Ó Donnchadha believed that many more had been lost and Flower (qv) notes that many of his manuscripts were written for priests in local parishes. The oldest extant copy of Parlaimint na mBan was transcribed by him in 1723 (NLI). This same manuscript also contains the oldest copies of Agallamh na bhFíoraon and of Fr Conchubhar Mac Cairteáin's sermons. Ó Conchúir suggests that the material in this manuscript may have been transcribed from a manuscript belonging to Mac Cairteáin. In 1725 he copied poetry and prose stories from a manuscript by Dáibhí Ó Bruadair (qv). It is noteworthy that he composed a lament for Ó Bruadair's son, Uilliam, who died 1 January 1729. The manuscript BL Egerton 211 was written in 1758 for Muiris Ó Conchubhair, a Cork shipwright.
Ó Murchadha also played an important role in the cúirt éigse of the Blarney area and was in contact with other poets and priests of the time. Fr John O' Briain (qv) (afterwards bishop of Cloyne), spent a number of years in Carrignavar parish and a close friendship developed between them. They regularly wrote verses answering one another. Ó Murchadha sent Seán Clárach Mac Domhnaill (qv) a poem entitled ‘Beannacht le searc' while the latter was visiting Ó Murchadha's landlord and friend Cormac Spáinneach in 1743. He also composed an elegy on MacDomhnaill's death in 1754. His contact with other poets included Éamonn de Bhál (qv) and Liam Rua Mac Coitir (qv). The elegy ‘Is cumha ‘s is ceas’ was composed on Mac Coitir’s death in 1738.
Ó Murchadha had a habit of keeping a pocket notebook in which he wrote songs and verse he had just composed. His notebook for the period 1720 to 1745 is still extant and provides an important insight into Gaelic cultural life at the beginning of the eighteenth century.
He composed only one Jacobite poem entitled ‘Tá an bhliain seo ag teacht’ and composed no political poetry after 1745. His fellow poet Pádraig Ó Súilleabháin criticised him for not having composed any poem ‘ag trácht ar mhnaoi gan chéile’ (‘dealing with a woman bereft of her spouse’), i.e an aisling. Ó Buachalla has termed him the most apolitical poet of his time and noted that he composed for a restricted audience comprising the gentry, clergy and poets of his native area.
Ó Murchadha married around 1725 but his wife's name is unknown. They had six daughters and one son, Pádraig. His wife contracted smallpox in 1728 and he composed a petition to St Gobnait for her recovery: ‘A Thríonóid Aoird (mo pheitision chun na Banaomh Gobnatan, et cetera, an tan do ghabh bolgach mo bhean, 7 November 1728)’. The following year, he also contracted smallpox and lost his hair as a result. He requested the loan of a wig in verse from Fr Seosamh Mac Cairteáin – ‘Is níor mhór dhom seana-wig sealadh mar scáth dom’ phlaosc’; (‘I need an old wig for a while as a cover for my head’) and Tomás de Barra – ‘Do gheallais dom bán-wig álainn d’oirfeadh dom' chluais, /Ó scaipeadh chun fáin gan fagháil gach ribe dhem' ghruaig’; (‘You promised me a lovely white wig that would fit my ears/ since every strand of my hair was dispersed far and wide’).
On Mac Coitir's death in 1738, Ó Murchadha was elected chief poet of the Blarney, Whitechurch and Carrignavar cúirt éigse. He was appointed as a cleric or bailiff in the Glanmire court in 1739 and composed a poem welcoming the chief sheriff Sir John Colthurst from Cork. He remained in the post for three years but does not appear to have enjoyed his work there: ‘Rithfead dom gháirdín, ránn mhín glacfad mar riaghail, / Is cuirfead an bháillidheacht fá thrí i n-ainm an diabhail’; (‘I will run to my garden, take shovel in hand, and the devil with being a bailiff’).
Ó Murchadha died in September 1762 in the Carrignavar/Whitechurch area and was interred in Whitechurch.