Arthur Schlesinger Jr. first met Robert F. Kennedy during Adlai Stevenson’s second run for the White House, in 1956. Schlesinger had been one of Stevenson’s senior advisers, while Kennedy, with his father’s connivance, had been an apprentice of sorts, tagging along and picking up pointers on how to run—and not run—a national presidential campaign. This was something Bobby’s old man figured might come in handy, and soon. “A long, rather sullen and ominous presence,” was how Schlesinger later described young RFK. “Kennedy and I regarded one another with great suspicion and barely spoke.”

Schlesinger didn’t mention their encounter in his journals. That mammoth chronicle, over which he labored for decades and which now takes up ample shelf-feet at the New York Public Library (the published version from 2007, edited by two of Schlesinger’s sons, represents only a tiny fraction of the original 6,000 pages), had not yet begun in earnest. That started—fittingly, given Schlesinger’s fascination with power—only around 1960, when the Harvard historian finally went with a winner: Senator John F. Kennedy, who brought Schlesinger into his circle, and then into his administration, for his Harvard pedigree, intellectual heft, and stalwart liberal credentials. Only then were there matters of moment to record, at least some of them involving Schlesinger himself. And because they’ve scarcely been mined, for anyone writing about Robert F. Kennedy—in my case, for a book about his relationship with Martin Luther King Jr.—the journals offer a ready source of insightful, clever, catty, and original material. 

Bobby Kennedy was plenty important to his brother, first running his campaign, then becoming his Attorney General. But judging from the paucity of entries mentioning RFK, Schlesinger was slow to notice or care. Perhaps the old skepticism, and resentment, lingered. Or maybe, he remained unimpressed: Schlesinger had his snobbish side, and even when Bobby became a person of consequence, he remained in Schlesinger’s eyes less charming, dazzling, sophisticated, intelligent, and good-looking than his big brother. As a journal entry from January 1965 makes clear, Schlesinger (who’d gone to Harvard with Joseph Jr., killed during World War II) felt Joe and Rose Kennedy had reaped ever-diminishing returns from their surviving successive sons. “Teddy is a fine fellow, but he is much further below Bobby in ability than Bobby is below JFK,” he wrote.  

But over the next three and a half years, something dramatic happened. As Robert Kennedy grew, Schlesinger’s affection, respect, and admiration for him grew, too. No doubt, this reflected Schlesinger’s own needs: after a career in the backwaters of Cambridge, Schlesinger was seduced by the power and glamour of Washington, D.C., and Bobby Kennedy provided him with an entrée back into the world of influence that had been so suddenly and cruelly wrested from him by what RFK always called “the events of November 1963.” But it wasn’t only that. As so many others eventually did, including many normally world-weary journalists, Schlesinger fell for Robert Kennedy. 

More improbably, though, Schlesinger also came to respect Bobby—more, even, than he had respected his older brother. “It will be a long time before this nation is as nobly led as it has been in these last three years,” he’d written, in shock and sorrow, on November 22, 1963. But only four and half years later, he had changed his mind. ...