It is not only Presidents whose reputations can soar once they leave office. So, too, can the public regard for their spouses - as attested by the transformation of how America views Nancy Reagan, once the scarlet woman of the White House, now the a wife and widow presented as a role model for a nation.
Yesterday, all eyes were upon her as Ronald Reagan's coffin was taken to lie in honour in Simi Valley, in his adopted California. This Friday, as heads of state and government from around the world assemble for Washington's first Presidential state funeral since Lyndon Johnson died in 1973, she will be the face on which the cameras linger in National Cathedral.
Today, Mrs Reagan is 82 and, if allowance is made for the passage of the years, physically not very different from the First Lady who flew back west with her husband after eight years in which they had been America's equivalent of monarchy. But the country now looks on her very differently from the way it did two decades ago.
Mr Reagan himself had undergone an astonishing rehabilitation, his image gradually changing from semi-comatose Cold War warrior to the man who turned the modern Republican party into the force it is today and brought Communism to its knees. Today he is reckoned among the two or three most important US Presidents of the 20th century.
And so, in a different way, it has been with Nancy. The hard- edged virago of yesteryear has been reconfigured as a latter-day saint, nursing her husband through an especially cruel and destructive illness, a champion for the millions who suffer from Alzheimer's.
These days, it is hard to remember the old Nancy, the woman reputed to have regarded White House as an extension of a glamorous Hollywood party. Her twin obsessions were socialising and ruthlessly protecting her husband from anyone or anything of which she disapproved, even if the interests of state might dictate otherwise. If she had her doubts, she would resolve them by consulting the stars.
Between 1981 and 1989, Nancy Reagan was the First Lady of whom they walked in dread. Kitty Kelley, the queen of slash-and-burn celebrity biographers, depicted her as a Hollywood starlet with a racy past and an eye for the main chance. As Ms Kelley tells it, The young Nancy Davis set her sights on Ronald Reagan from her very first glimpse of him in 1949. She was the ambitious California governor's wife - a vain and relentless social climber, a formidable political operator and bitter enemy of anyone who crossed her. Nor, if the biography is correct, was she quite as perfect a wife as generally believed. Ms Kelley writes breathlessly of alleged White House encounters between Nancy and Frank Sinatra, which not even her husband was permitted to interrupt.
Her grudges, too, were legendary, and none more so than the one which grew out of her rivalry with Raisa Gorbachev. Raisa was herself an exception to every rule, the first non-dowdy, non-self effacing Soviet leader's wife, with a PR sense as keen as Nancy's own. Raisa trumped Nancy by appearing, unscheduled, at the Reykjavik nuclear arms summit of 1986 and Ms Reagan never forgave her for that act of one-up-womanship.
The following year when Mikhail Gorbachev came to Washington (with Raisa) the First Ladies' show was an attraction to rival the epochal arms cutting treaty signed by their spouses.
Also, Don Regan, the White House chief of staff during Mr Reagan's far less effective second term, recounts how Nancy badgered him to get rid of William Casey, the then CIA director, even as he lay on his deathbed.
The episode might be attributed to Mrs Reagan's all-eclipsing obsession, to protect her husband and his reputation - indeed she was even said to have initiated the transformation of Reagan the warmonger, of "Evil Empire" fame, into Reagan the peacemaker, who would leave office dreaming of a world without nuclear weapons. …