Brian O'Nolan, who used the pseudonyms Flann O'Brien (for his novels) and Myles naGopaleen (for his newspaper columns), was born in 1911 in the north of Ireland. His father, a career civil servant, was a fervent Irish linguist who educated his sons at home because he did not want them to be taught in English. O'Nolan grew up mainly in Dublin and was educated at University College Dublin and, like his father, entered the Irish civil service. His first book, At Swim Two Birds (1939), was edited by Graham Greene and greatly admired by James Joyce, who called O'Nolan ""a real writer, with a true comic spirit."" This was to begin O'Nolan's love-hate relationship with Joyce. He was a Joycean apostle, but, in time, he grew weary of hearing how his writing style mimicked that of the master. In 1940, O'Nolan began writing a column for the Irish Times, and in 1941 published An Beal Bocht (translated as The Poor Mouth in English), a comic novel about the Irish-speaking west of Ireland. Cronin (Samuel Beckett: The Last Modernist), who was a friend of O'Nolan, focuses on many aspects of the novelist's life: his friends, who considered him a ""natural celibate"" (although he married later); his relationship with Sean T. O'Kelly who would become president of Ireland; how he savaged parts of his novel, The Third Policeman, to put together his later work, The Dalkey Archive; his friendships with William Saroyan and Brendan Behan; and his alcoholism, which led to the cancer that killed him in 1966. Cronin also presents a vivid picture of Dublin life in the middle of the 20th century, identifying pubs--many of which still operate--that will be of particular interest to O'Nolan aficionados. This is an intense look at one of 20th-century's Ireland's greatest writers that will appeal to fans and scholars alike. Photos. (Mar.) FYI: Dalkey Archive, the Chicago-based press, is named after the comic novel whose hero is James Joyce.