As a young man, Robert A. Caro was a newspaper reporter.
Caro is the painstaking, some would say obsessive (though he has always denied it) writer, whose first book, “The Power Broker, a 1,336-page biography of Robert Moses, took him seven years to complete — after which he turned to his true life’s work (perhaps even his true obsession), a multivolume biography of Lyndon Johnson, the fourth volume of which, “The Passage of Power,” has just been published to great acclaim, reviewed in The New York Times by none other than former President Bill Clinton and which has been 36 years in the making. So far.

Working for a newspaper meant meeting deadlines, deadlines that, yes, allowed the paper to come out the next day, but also meant, all too often, compromises. Caro couldn’t repeat himself in a newspaper article; he couldn’t say the same thing five, six, seven times, until he was sure — absolutely sure — that the reader got the point. He couldn’t include all the many stray facts he had uncovered. Sometimes, words even had to be cut from a Robert A. Caro newspaper article — cut ruthlessly, mercilessly, by editors who didn’t understand the importance of those words, or the significance of those seemingly stray facts.

But once Caro turned to books, and, especially, once he began working on his L.B.J. biography in the mid-1970s, all the previous obstacles fell away. He would spend years — nay, decades — in the field, finding stray facts no one else had ever known existed. And then, when he started writing, he couldn’t stop. Other, lesser authors had deadlines, but not Caro. He turned in each volume only when he was ready, and sometimes a decade passed between volumes — so much time, in fact, that he began quoting his previous books in his newer books. Originally intended to be three volumes, written over maybe a half-dozen years, his L.B.J. biography eventually stretched to four, and then five. The fifth, which Caro has yet to write, is supposed to be the last one.
There was something unquestionably awe-inspiring about Caro’s quest to create a biography as big as Johnson’s life. The third volume, especially, entitled “Master of the Senate” — Caro’s 1,167-page account of Johnson’s years as the Senate majority leader — was immediately hailed as one of the greatest illuminations of power ever written.

But was there also something about Caro’s pursuit of L.B.J. that was just a little bit Ahab-like?
“I can’t imagine this being done or even attempted by anyone else,” his publisher, Sonny Mehta, told Esquire magazine. “He’s given over so much of his life to another guy.” Mehta meant it as a compliment, but it did make you wonder: Was any biography worth nearly half the writer’s life? To write his new book, which weighs in at a mere 712 pages, Caro spent 10 years recounting just six years, from 1958 to 1964, three in which very little happened, since, as John F. Kennedy’s vice president, Johnson had little to do. Yet every time you had a thought like that, you hit a chapter that reminded you anew of Caro’s literary powers. In “The Passage of Power,” for instance, Caro retells the Kennedy assassination — a story that has been written hundreds of times before. Yet Caro makes it feel completely fresh, spellbinding even.

There were other problems, however.
In the first two volumes, published in 1982 and 1990, Caro’s Johnson is a man with a “hunger for power in its most naked form, for power not to improve the lives of others, but to manipulate and dominate them,” as Caro wrote in “The Path to Power,” the first volume. Johnson has almost no redeeming qualities in the first two books. Yet how could this same man, at the end of Volume 4, push through the landmark Civil Rights Act as president? How does Caro square this great achievement — as well as all the other liberal achievements to come — with his portrayal of the power-mad Johnson in the earlier volumes?

In truth, he never really does. If the Johnson of Volumes 1 and 2 is the “bad” L.B.J., then the Johnson of Volume 4 is the “good” one. It is almost as if Caro is writing about two different people — as if, for all his reportorial skill, he can’t countenance Johnson being both ruthless and compassionate in the same volume. He has to be one or the other.

So here we are — and here he is, at the age of 76 — four volumes later, and there is so much more yet to tell. Caro still has the Goldwater race to cover, and the legislative achievements that follow. And, of course, there is still Vietnam to write about. Nearly half a life later, in other words, Caro is finally getting to the heart of the matter.
One could imagine other writers managing to squeeze it all into the one final volume being contemplated. But Robert A. Caro? Not a chance.