After meeting Khrushchev at a summit in Vienna in June 1961 -- a tense meeting where the Soviet premier tried to bully the young president who was weakened by the failed Bay of Pigs invasion -- the president confided his private worries.
"It's going to be a cold winter," she recalled him telling her. "And he said that in really scared -- then I just think you'd seen just naked, brutal, ruthless power… Khrushchev thought that -- saw that perhaps he could -- thought he could do what he wanted with Jack."
But when Mrs. Kennedy chatted with Khrushchev, it was about a novel she'd recently read about the Ukraine. She recalls how her forced conversation with the Khrushchev led her to offhandedly ask for a puppy from a litter one of the Soviets' famous space dogs had just had.
President Kennedy was more than a little surprised when "this poor terrified puppy" suddenly was delivered to the Oval Office, delivered by the Soviet ambassador to the United States, she said.
Yet for all her involvement inside her husband's White House, Mrs. Kennedy espoused views toward marriage and gender politics that seem dated to modern ears. In fact, she'd live long enough to reverse some of those views quite thoroughly, as historian Michael Beschloss notes in the book's introduction.
"I think women should never be in politics. We're just not suited to it," she told Schlesinger at one point.
Schlesinger chose not to ask Jacqueline Kennedy about the events in Dallas on Nov. 22, 1963. Those questions were left to author William Manchester, who was writing an authorized book about the killing, and the Warren Commission, the presidential inquiry into the assassination.
But Mrs. Kennedy twice brought the assassination up on her own in reference to a recent Supreme Court ruling protecting free speech. The case, she said, reminded her of ads in Dallas newspapers around the time of Kennedy's assassination. One had a picture of the president and the text, "Wanted for Treason."
"When you think, ads like that in the paper was partly what killed Jack," Mrs. Kennedy said.
She voiced particular frustration that one of President Kennedy's own court appointees, Arthur Goldberg, took a position to support unfettered free speech in that case.
The tapes provide an unvarnished view of some of the world's leading mid-century figures, with biting assessments of, among others, Martin Luther King Jr., and two other first ladies, Lady Bird Johnson and Mamie Eisenhower.
She recalls her husband's disappointment when he finally met his hero, Winston Churchill, as a senator in the late 1950s.
"Jack had always wanted to meet Churchill. Well, the poor man was really quite ga-ga then," she said. "I felt so sorry for Jack that evening because he was meeting his hero, only he met him too late."
Her own hero, French President Charles de Gaulle, she ultimately found to be a "spiteful man."
Mrs. Kennedy also described a president who coped with wrenching back pain for much of his adult life.
"Jack could never touch his toes. He couldn't get his hands down any farther than his knees standing up," she said. "He could never put on his shoes before -- sort of bend over that far."
"Once I asked him -- I think this is rather touching -- if he could have one wish, what would it be? In other words, you know, looking back on his life, and he said, 'I wish I had more good times.'"
But with a new treatment regimen in the White House, she said, "He was never in better health or spirits than all his White House years."
That left her hopeful for a healthy post-presidency: "It just made me so sad, because Jack could have had his happiest years later."