Despite the international recognition that Conor Cruise O'Brien has won in his long career as diplomat, scholar, politician and journalist, there is a dimension to him that must surely escape those who are not Irish. The mere mention of his name or the sound of his voice evokes an intimate, ethereal presence. A generation of Irish who grew up in the 1970s cannot forget that voice: cool and steely, a touch superior even, possessed of a disturbing, alien rigour. Others might write of how Ireland was burdened by pieties; O'Brien made you feel the weight of them.
In British common rooms, on American campuses and across African capitals, O'Brien is known as the unreliable UN diplomat who came unstuck in Katanga, the one-time anti-Vietnam war demonstrator in the streets of New York, the anti-anti-communist, the resolute defender of Israel, the champion of Edmund Burke and the demolisher of smug utopianism. But these readers and audiences are often immune from the psychic disturbance that his utterances can provoke among his compatriots.
In 1974, for instance, when I was at school and O'Brien was a minister in the Irish government, the elderly Christian Brother who led us in reciting the Angelus at noon each day would pause after the last Hail Mary. Head bowed, rough hands crossed over his black soutane, he would then intone quietly: "And now let us say one more Hail Mary for the conversion of Conor Cruise O'Brien." I've never worked out if that was terror of an infidel speaking or actual sadness.
O'Brien, a half-Catholic (his father was an agnostic), attended a Protestant school. "Somewhere in there at the levels of the psyche I am trying to explore was the notion that religion and nationality were like lungs," he writes in this memoir. "One lung [religion] was gone - it might be aptly described as past praying for. If you lost the other you would be finished." No sooner had he discarded the lung of religion than he set about persuading the rest of the Republic of Ireland that they would breathe easier without it, too. And in his 82nd year, he now advises that the unity of Ireland is the best way to save unionism.
O'Brien's attachment to such dramatic reappraisals is now part of his personality. After his return to Ireland from his spell as Albert Schweitzer professor of humanities at New York University, he embarked on a complete rethinking of his nationality, rejecting in the brilliant polemic States of Ireland the sacred principle of the thwarted Republic: unity of North and South. He performed this task with such diligence and energy that even one of his admirers, the historian John A Murphy, accused him of demolishing people's self-confidence in their own nationality.
O'Brien's own self-confidence was unharmed by the hatred he had to endure for his act of apostasy. The reason he could sustain it is clear from the richest chapters of this book, those about his family and upbringing in the genteel Dublin suburb of Rathmines. His grandfather had been an Irish Parliamentary Party MP. He writes wistfully that if Home Rule had been achieved and the violent uprising of 1916 had never happened "our whole family would have been part of the establishment of the new Home Rule Ireland". Dispossession seems to have had little effect on the family's sense of pride and distinction. The O'Briens felt so secure about the eminence of their ancestors that Conor's fearsome Aunt Hanna referred to the Protestant settlers who supplanted them as "Cromwell's little drummer boys".
An only child, O'Brien was adored by his father. One of the most affecting passages in the book is the description of the death of his father on Christmas Day in 1927. That devastating childhood blow is cruelly echoed at the end of his life - the opening pages describe how, when visiting his daughter Kate, editor of this memoir, to celebrate its near completion, he found her dying of a stroke on the floor of her house.
O'Brien throughout strikes the right note, an unsentimental, colloquial retelling, brimming with emotion. The humorous, barbed anecdotes about colleagues and adversaries in a life devoted to sowing controversy are delivered in the same engaging style. It is unlikely that any other Irish public figure would be so joyful about his ability to attract enemies. One feels that, in some way, O'Brien needed enemies - in the United Nations, in the Dublin cabinet, at the Observer, where he was editor-in-chief - against whom to define himself and fashion his triumphs. One of his most notable stands was his effort to implement the United Nations mandate to end the secession from the Congo of the British- and Belgian-sponsored puppet state of Katanga. Out of his defeat, the result of covert manipulations and betrayals, came his best book, To Katanga and Back. It is a wondrously plotted dissection of imperial meddling and UN weakness before the weight of the great powers. Long sections of it are reprinted in the memoir to cover his UN episode - a disappointing shortcut if you've read the original book, but an invitation if you haven't.
Reading To Katanga is an antidote to the darker side of O'Brien that emerged when he was a member of the Dublin government. Possessed at that stage by a febrile premonition of civil war in Northern Ireland and a sense that the IRA posed a powerful threat to the Republic itself, he exercised moral and political authority towards stamping out any expression of even unwitting support for subversion. In retrospect, he is insouciantly unapologetic about this departure from his liberal creed, even confessing that he wasn't bothered when told that Irish policemen had "beaten the shit" out of an IRA sympathiser.
The writer Seamus Deane has complained that O'Brien's humanism is utterly detached from its atavism - by which he means, I suppose, that he is estranged from the intuitive attachments of common people in Ireland and elsewhere. I don't think that this is the case and there are many passages here to contradict that line.
Whether O'Brien is right or wrong on a particular question is not really the issue. In1966, lecturing on Burke and Marx, he declared that these figures may not be reliable guides to the 20th century, but that their importance lay in "the manner and intensity of their coming to grips [with reality] - an example of intelligence fired by passion". Intelligence fired by passion - this would do as O'Brien's epitaph.
Maurice Walsh is a BBC foreign correspondent