The historian Michael Beschloss has observed that after twenty-four-year-old Theodore Sorensen joined Sen. John F. Kennedy’s staff in 1953, “the hackneyed speeches of Kennedy’s congressional years gave way to the staccato phrases, contrapuntal sentences, soaring rhetoric, and quotations from the great for which Kennedy would always be remembered.” But Ted Sorensen proved to be more than just a gifted speechwriter. During JFK’s presidency he became a trusted adviser, brought in on virtually all difficult matters, foreign and domestic—“a very important figure,” Robert F. Kennedy would judge, looking back in 1964.

Once JFK’s brief presidency was over, Sorensen’s continuing loyalty to the president he revered did not serve him particularly well as an author. His massive monument to the fallen leader, Kennedy (1965), offered compelling accounts of the Cuban missile crisis and other charged international moments, but otherwise was unrevealing and soporific. And as for his treacly The Kennedy Legacy (1969), Sorensen himself now acknowledges that the book “deserved much of the scorn heaped upon it by some reviewers.” Decades later, however, the passage of time, the loss of his ambition for political preferment, the death of Jacqueline Kennedy Onassis, and the many disclosures already made by others have freed Sorensen to write with more ease and candor. The result is a splendid memoir, Counselor.

The book starts with a look back at Sorensen’s youth in Nebraska—his father, C. A. Sorensen, was a politically active lawyer who sailed on Henry Ford’s “Peace Ship” and later served as the state’s attorney general—and ends by chronicling his post-JFK life in New York, including his years with a high-powered law firm, his ill-fated 1970 bid for the Senate and thwarted 1977 nomination to head the Central Intelligence Agency, and the 2001 stroke that left him with severely impaired vision. But the memoir’s longest section, naturally enough, takes up its author’s years with JFK, including the drama of the 1962 Cuban missile crisis.

Proud as he is of his role in helping resolve the crisis, Sorensen is no longer sure that risking nuclear war to resolve it was justified. Looking back, he sees Kennedy and Soviet leader Nikita Khrushchev caught in a dangerous stalemate: Khrushchev insisting that the missiles in Cuba merely balanced NATO missiles in Turkey, and reluctant to appear weak to his Chinese and domestic critics; Kennedy for his part concerned that the confidence of Western allies depended on his not looking soft in the face of this threat. “Were both men now thinking the unthinkable and gambling on world survival largely for reasons of appearances?” Sorensen asks. “If so, that is indefensible in hindsight.” Retrospect has made the counselor more dovish. Sorensen acknowledges that if Kennedy had essentially done nothing about the missiles—an option seriously considered by some advisers—he would have been severely criticized by “hard-line super-patriots.” But in the face of possible nuclear war, he argues, such political damage “would have been by comparison a minor and transitory risk.”

Sorensen counts Kennedy’s national address on the missile crisis as one of his three most important speeches. The others were his 1963 televised address urging the moral imperative of civil rights (which, Sorensen now acknowledges, JFK had been slow to recognize) and his 1960 speech to the Houston Ministerial Association, defending the ability of a Catholic to serve as president without divided loyalty. In that address, Kennedy spoke of an America “where the separation of church and state is absolute, [and] where no Catholic prelate would tell the president—should he be a Catholic—how to act.” Almost half a century later, Sorensen insists that neither he nor Kennedy intended these comments to mean that moral issues should be kept out of the public square, or that thoughtful clerical views on such issues should not be heard.

A Unitarian whose faith includes a belief in “the essential goodness of human beings,” Sorensen relates an amusing anecdote on the subject of religion. As he and Kennedy were en route to Houston and working on the final draft of the church-and-state speech, Kennedy laughingly asked whether any of his Catholicism was rubbing off on Sorensen. “No,” Sorensen replied, “but I think some of my Unitarianism is rubbing off on you.” And undoubtedly it was—at least on Kennedy’s speeches. “Many of the speeches that I drafted reflect Unitarian principles,” Sorensen acknowledges. As for his influence on his boss’s politics, he confesses that over time he “gradually...crafted a more liberal perspective into some of his speeches.” Of course, he could hardly have done that without Kennedy’s assent. Still, Sorensen was very aware of having influenced Kennedy—so much so that a friend once remarked that the speechwriter looked on the president as “his work of art.”

When public viewing hours were over, however, the work of art stepped off his pedestal and lived by his own lights; Counselor confirms that the two men’s intellectual camaraderie did not extend to private life. “Throughout our years together...I was totally involved in the substantive side of his life,” Sorensen writes, “and totally uninvolved in the social and personal side.” A serious-minded, abstemious intellectual with limited social skills, Sorensen worked long hours for Kennedy—badly neglecting his family in the process—but “never felt entirely comfortable with the cool crowd” in his chief’s after-hours world.

As for Kennedy’s philandering, in retrospect Sorensen views it as “self-indulgent....misconduct” whose inevitable disclosure threatened to “diminish the moral force and credibility of all the good he was doing.” But Sorensen insists that, to the best of his knowledge, Kennedy’s private misconduct did not in fact interfere with “the fulfillment of his public duties.” Apparently Sorensen does not consider that the reappointment of FBI Director J. Edgar Hoover, which he laments, might well have been due to the evidence Hoover had amassed of that misconduct. Nor does he address the risk that embarrassing revelations might have posed to a second Kennedy term, potentially making it less than the “triumph” Sorensen is confident it would have been.

Of course, that second term never happened, rendering such judgments hypothetical and leaving many questions unanswered, among them the biggest and most tantalizing of all: Had JFK lived and been reelected, what would he have done about Vietnam? Would he have gotten us out? Looking back, Sorensen notes that Kennedy “made many conflicting statements, both public and private,” on both sides of the question—even as the number of U.S. military advisers in Vietnam rose to over sixteen thousand at the time of his death. “I would like to believe that Kennedy would have found a way to withdraw,” Sorensen writes. And yet he cannot say so with certainty. “I do not believe he knew in his last weeks what he was going to do.”