The Book of Dimma (Dublin, Trinity College, MS.A.IV.23) is an 8th century Irish pocket Gospel Book originally from the Abbey of Roscrea, founded by St. Cronan in the County Tipperary, Ireland. In addition to the four Gospels, in between the Gospels of Luke and John, it has an order for the Unction and Communion of the Sick. It was signed by its scribe, Dimma MacNathi, at the end of each of the Gospels. This Dimma has been traditionally identified with the Dimma, who was later Bishop of Connor, mentioned by Pope John IV in a letter on Pelagianism in 640.
The illumination of the manuscript is limited to illuminated initials, three Evangelist portrait pages and one page with an Evangelist's symbol. In the 12th century the manuscript was encased in a richly gilt case.
In the old kingdom of Eile O'Carroll there were several Christian Saints. One was St. Cronan, who requested that the famous Book of Dimma be written. The Book of Dimma is an Irish manuscript of the Four Gospels written in the seventh century. The Book is currently at Trinity College in the City of Dublin, Ireland. The box containing the manuscript is charged at either end with a lion rampant, with the outer compartments charged with lions passant.
The Book was earlier preserved by Thady O'Carroll, Prince of Ely during the mid-twelfth century, and afterwards at Roscrae. The three Effigies contained are St. Matthew, St. Mark, and St. Luke. John is represented by an eagle. The Cross of St. Cronan shows a circle around the arms of the cross, with a figure on both sides of the cross. One figure represents Christ, the other being St. Cronan. One of the foundation stones of the Abby next to St. Cronan's Cross bares an Irish inscription. It reads: " Pray for O'Carroll, King of Eile." He was the Abby's founder.
The Éile, the Iron Age tribal group from which the Uí Chearbhaill (O'Carroll) emerged, are immortalised in the ancient place name Bri Éile, now Croghan Hill in north County Offaly, and Moin Éile, the 'Notorious Red Bog of Ely' as Sir William Petty and his wary surveyors described it in 1657. Éile was a territory between Lough Derg on the river Shannon and the Slieve Bloom mountains. The territory consisted of Lower Ormond and the Ikerrin in north Tipperary together with Clanrisk and Ballybritt in south Offaly.
The Fiachach Eile (in north-east of Tipperary - Thurles and Roscrea) were descended from Deachluath, grandson of Eoghan Mor (ancestor of the Eoghanacta/Eugenians).
