This is not going to be one of those reviews that decry doorstop biographies. I promise. But surely comment is called for when the third and final volume of Norman Sherry’s opus (Viking, 800 pages, $39.95) equals in size Richard Ellmann’s “James Joyce.” Even if we grant Mr. Sherry his conceit that Graham Greene is a great novelist, should this biographer’s work be longer than George Painter’s “Proust” or equal in length to Leon Edel’s five-volume “Henry James”? Is Mr. Sherry in the same league as these renowned biographers? Does his method justify so many pages?

Mr. Sherry provides at the beginning of this volume a rationale for his epic size narrative:

It would have been easier to have had a specific point of view, to have looked at Greene through a template of excessive admiration or excessive hate (and indeed one memorialist has done the former, one biographer the latter). Such a method dramatically reduces the scope of research that is ultimately undertaken, since conclusions have already been reached before the research begins. If one is ready-armed to see only what one wishes to see, truth is never served. Using such a method, one is not looking for the complicated man standing there but only for the partial evidence which will either glorify or beggar the writer’s view of the nature of the subject.

In other words, to be open to the subject’s experience – especially to that of a writer who surely logged more miles in more parts of the world than any of his contemporaries – requires biography on an extraordinary scale. Mr. Sherry has himself become a fabled figure because of his willingness to retrace Greene’s voyages to the ends of the earth (as the biographer did in his two well-received books on Joseph Conrad’s eastern and western worlds).

But to whom is Mr. Sherry comparing himself when he refers to the hagiographical memorialist and the hostile biographer? I presume he has in mind Ronald Matthews, whose sycophantic memoir first appeared in France. An embarrassed Greene made Matthews agree to forego publication in English. Michael Sheldon is the only other biographer to complete a full-scale life of Greene, and given Mr. Sherry’s animadversions on excessive hate, I had to take a peek at the competition.

Before I did, though, I reflected that I could not recall a case in which a literary biographer began by loathing his subject. Quite the contrary, it is more likely that the biographer begins with excessive admiration and gradually becomes disenchanted – or at least chastened to discover that his subject is not a paragon. Lo and behold, this is what Michael Sheldon reported:

When I began work on this biography, I intended it to be a very favorable portrait of a novelist who deserved all the prizes the world could give him. I wanted to trace each step of his career with sympathy and point out his virtues as both a writer and a human being. But along the way, I kept uncovering unpleasant facts, and my understanding of Greene’s life and art gradually changed. I found a haunted character with many startling secrets, and I began to see that his work used an elaborate code to address these secrets. As more and more pieces of the code were broken, I realized that Greene was not the man he pretended to be, and that his work, too, has a disturbing underside to it, a side that reflected his personality even as he deceived us about it.

As an account of the biographer’s psychology, I find this passage exemplary. And I have read enough of Mr. Sheldon to know that he is no hater; rather, he came by the same hard, unsparing view of Greene and of humanity that the novelist himself possessed.

Struggling within Mr. Sherry’s bloated biography is Mr. Sheldon’s Greene, crying to get out. Both biographers present a man and a writer who was one of the century’s great deceivers – in the same league as his spook friend Kim Philby. In the face of all evidence to the contrary, for example, Greene continued to laud the Soviet Union and flatter Fidel Castro. There is a startling scene in Mr. Sherry’s book involving a Cuban official who tells Greene to his face that a part of his movie script set in Cuba has to be censored. While Mr. Sherry does not shrink from such damning scenes, he backs away from them by discussing Greene’s belief in disloyalty and duplicity.

Mr. Sherry contends that the only way for Greene to be his own man was through an act of betrayal. Greene spied for the British government but relished publicly attacking its policies. He made love to a woman, then told her part of his heart belonged to another. He engaged in this sort of two-timing repeatedly, and Mr. Sherry does not mind rehearsing episodes of his subject’s recurring equivocations even when he recognizes that the reader – like Greene’s lovers – wearies of them.

A beautiful Swedish actress told Mr. Sherry that she loved Greene but she was “too young” and he was “too cynical.” I daresay anyone having to grapple with Greene would feel too young or too innocent – and, in my case, too American, as well. Mr. Sherry assures us that Greene was not anti-American, but I must say that if Greene was ever pro-American, he did a wonderful job of hiding the evidence.

What makes a novel like “The Quiet American” (1955) so disturbing and memorable is that Americanness is equated with a human tendency to delude oneself, to believe in one’s virtue even while committing unspeakable atrocities. I do not like Mr. Greene’s version of the American psyche, but I nevertheless find his novel haunting and beautifully executed.

America, anyway, is not the Great Satan in Greene’s life and work. He could hardly live with himself, let alone others. His constant travel to France, Russia, China, Tahiti, the United States, Sweden, Jamaica, Mexico, Cuba, Panama, and many other parts – all the while setting his work in many of the places he visited – was, Mr. Sherry believes, connected to Greene’s efforts to suppress a suicidal nature. Greene, one of the world’s famous Catholic converts, loved to confess – not to priests but to lovers – and then to sin again. Indeed, his novels show an understanding of the tortured conscience that made priests want to confess to him. Mr. Sheldon presented this Graham Greene in a stark and persuasive 400-page narrative, which Greene spent years attempting to thwart. In his “Author’s Note: Graham Greene and Biography,” Mr. Sheldon showed how Greene and his estate staved off would-be biographers, settling finally in the mid-1970s on Mr. Sherry as the official biographer who would tie up important papers, have exclusive permission to quote from published and unpublished work, and have first crack at interviewing many people who would be dead by the time another biographer was on the case. “History would be recorded, but it would be one writer’s version,” wrote the undaunted Mr. Sheldon, whom I greet as a fellow old hand in the business of surmounting the barriers subjects and their estates erect to thwart the unauthorized biographer.

Greene chose his man well. Although Mr. Sherry exposes some of Greene’s “less pleasant qualities,” as Mr. Sheldon put it, the official biographer nevertheless encases the unpalatable in a good deal of obfuscation about his subject’s multiple selves and in Mr. Sherry’s indefatigable efforts to travel to “Greeneland,” as he calls it, and to unearth the originals or models for Greene’s characters.

Evidently Mr. Greene knew his anointed biographer would spend decades on his detective work. In fact, a good deal of Mr. Sherry’s to-ing and fro-ing occurred while his subject was alive. In 1985, novelist David Lodge observed that Greene “seemed to derive a mischievous glee from the tribulations that poor Norman Sherry had suffered in trying to retrace Greene’s every step.”

Indeed, if there is something heroic about a biographer who spends 30 years doggedly pursuing his subject, there is also something rather silly and futile about such elaborate exactitude. As Mr. Sherry concedes, the Greeneian landscape had changed by the time he arrived; it was not the world that the novelist experienced, although Mr. Sherry is adept at locating vestiges of Greenery (Greenish puns seem irresistible to whoever writes about GG).

Mr. Sherry comes no closer to the inner man than did Mr. Sheldon, especially since the former writes schoolboy prose and employs cliches: the “initial shot across the bow in the battle of censorship”; “entered the lists to do battle”; “twists helplessly in the breeze.” And there are other basic book-management problems. For example, there is a chapter devoted to analyzing similarities between Greene and the actor Paul Scofield. I fail to see the similarities or to understand why the biographer addresses an entire chapter to them. Indeed, Mr. Sherry is always asking questions because he cannot figure his man out – and how delighted that would have made Graham Greene (who, in fact, lived to see publication of Mr. Sherry’s first volume).

On the question of Graham Greene’s career as a British spy, Mr. Sherry cannot say any more, really, than Mr. Sheldon. Both biographers are stymied by their devious subject, and by a British government that is not about to come clean on Greene – even if that government could really know what this faithless man was up to.

I use the word faithless advisedly. It is one Greene often applied to himself. If ever there was a subject who thwarted the very idea of biography, Graham Greene is he.