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. Crónán in County Tipperary, Ireland. In addition to the Gospels of Luke and John, it has an order for the Unction and Communion of the Sick. The surviving illumination of the manuscript contains a number of illuminated initials, three Evangelist portrait pages, and one page with an Evangelist's symbol. The pocket gospel book is a distinctively Insular format, of which the Stowe Missal and Book of Mulling are other leading examples.[1]
The gospels other than John are "written for the most part in a rapid cursive script", while John is "by a different scribe, in neat minuscule bookhand".[2] It was signed by its scribe, Dimma MacNathi, at the end of each of the Gospels. This Dimma has been traditionally identified with a bishop who was later Bishop of Connor, mentioned by Pope John IV in a letter on Pelagianism in 640. This identification, however, cannot be sustained.