Proinsias Mac Cana, who has died aged 77, was one of the foremost Celtic scholars of his generation. Professor Emeritus of the School of Celtic Studies at the Dublin Institute of Advanced Studies, he previously held the chairs of Old Irish and Welsh at the National University of Ireland, Dublin.
His main field of research was early Irish tales, and the mythology informing them, and in this field he was pre-eminent. Another scholarly concern was the role of the filí in both Gaelic and post-conquest Ireland.
He broadened and deepened the understanding of the links between the languages, cultures and traditions of the Celtic peoples of Ireland and Britain. And through his scholarship and teaching he was an interpreter of the Irish to the Welsh and of the Welsh to the Irish.
He was born in Belfast on July 6th, 1926, the son of George McCann and his wife, Mary Catherine (née Mallon). He attended St Malachy's College and was a student of Queen's University Belfast, excelling not only academically but also as a heavy welterweight boxer of exceptional promise.
Awarded a BA degree with first-class honours in Celtic languages in 1948, he spent a year at the Sorbonne and grew so fond of Paris that he returned there regularly. In later years, working quietly in the background, he played a major role in the restoration of the College des Irlandais.
Returning to Belfast, he pursued research at Queen's and in 1951 was appointed assistant lecturer in the Celtic department. He secured an MA at Queen's in 1950 and in 1953 completed the PhD degree.
From 1955 to 1961 he taught Old and Middle Irish at the University of Wales, Aberystwyth, placing the teaching of Irish on a solid foundation and attracting excellent students. He was from 1961 to 1963 professor of Celtic studies at the Dublin Institute of Advanced Studies.
Following eight years as professor of Welsh at University College Dublin, he was in 1971 appointed professor of early Irish.
He returned in 1985 to the Dublin Institute of Advanced Studies as a senior professor in the School of Celtic Studies and was for some time director of the school. Between 1987 and 1992 he spent a semester each year as visiting professor in the Department of Celtic at Harvard University.
His many books and articles demonstrate scholarship of extraordinary depth and range.
His first book, with Tomás Ó Floinn, and illustrated by Micheál Mac Liammóir, was Scéalaíocht na Ríthe (1956), a collection of early Irish tales translated into modern Irish. Other books include Celtic Mythology (1970), The Learned Tales of Medieval Ireland (1980) and Literature in Irish (1981).
He was a contributor to Celtica, Études Celtiques, Studia Celtica and other journals. His article for the Crane Bag in 1978, Notes on the Early Irish Concept of Unity, was influential in promoting the notion of a cultural unity as distinct from a political unity.
In it he wrote: "Throughout the visible history of Irish tradition the palpable mark of the cultural unity of the island was the learned, literary language fashioned and cared for by endless generations of druids and filí."
One might reflect, he concluded, "on the curious contradiction between the traditional view that cultural unity could dispense with political unity and the modern nationalist view which glorifies political unity irrespective of cultural disparities".
On a lighter note, he was the true author of the oft-quoted witticism that to an Irishman the word mañana conveys a wholly unacceptable sense of urgency.
During his years in Aberystwyth he learnt to speak Welsh fluently, and with grace and verve. He began to investigate Welsh topics. His second book was on the tale of Branwen and his fifth on the corpus of tales known as the Mabinogion.
He was also a leading authority on Middle Welsh syntax and published more than a dozen important articles in the field. He consistently supported and encouraged Welsh and Celtic studies in Wales.
Welsh-language radio and television frequently called on his expertise as a knowledgeable and perceptive commentator on Irish affairs.
President of the Royal Irish Academy from 1979 to 1982, he was made a member of Academia Europaea, and a foreign honorary member of both the American Academy of Arts and Sciences and the Gustavus Adolphus Academy, Uppsala. He was given honorary doctorates by Dublin University, the University of Ulster and the University of Wales.
Most recently he chaired the editorial boards of two major RIA publications, the Dictionary of Medieval Latin from Celtic Sources, one of 15 similar national projects, and the Dictionary of Irish Biography (both forthcoming); he had been since 1973 co-editor of Ériu, the RIA journal of Irish studies.
He had a holiday home in the Donegal Gaeltacht and in the 1970s was a supporter of Gluaiseacht Cearta Sibhialta na Gaeltachta. Known for his courtesy, modesty and ordinariness, he was interested in most sports and enjoyed walking the East Pier at Dún Laoghaire.
He married in 1952 Réiltín Supple, who with their daughter, Máire, and son, Fiachra, survive him.
Proinsias Mac Cana: born July 6th, 1926; died May 21st, 2004