Just weeks before the election, the political world convulsed with the news that Walter Jenkins, the Johnsons’ closest aide, had been caught having sex with another man in the basement of a Washington YMCA. Lady Bird urged her husband to show public support and compassion for a man who had served their family for decades. When he refused, Lady Bird defied the advice of his counselors and released her own public statement: “My heart is aching today for someone who has reached the end point of exhaustion in service to his country.”

In the course of the ‘64 campaign, Lady Bird displayed a deep realism about human nature that is far more rare in a First Lady than we might think. President Obama, like his predecessors, promotes his wife as a source of real-talk, the one person who is unimpressed by his office and still gives it to him straight. But a First Lady, like any spouse, often feels the criticisms of her husband more acutely than does the president himself. A bunker of denial and recrimination can be an enticing escape for both partners in a political marriage. Hillary Clinton provided many assets to her husband during their time in the White House, but relief from paranoia and self-pity was not among them.

Even Lady Bird’s powers had their limits. As the Johnson presidency wore on, Vietnam overwhelmed everything, including Lady Bird’s ability to cut through the illusions in her husband’s head. It is tantalizing to imagine an alternate history of the Johnson presidency in which the First Lady was empowered to help her husband in Vietnam the way she helped him in other areas.