Jackie Kennedy is back, but the world she knew as first lady is gone forever. The woman Mamie Eisenhower said looked "younger than Barbie," the fashion icon who didn't want to wear hats but capitulated at Jack's inauguration with a chic pillbox worn on the back of her head so it wouldn't ruin her bouffant hairdo, the widow who described her husband's administration as Camelot, a romantic notion as fanciful as the legend from which it was based, speaks again through a gossamer haze of pre-feminist politics. The seven-part interview the former first lady gave to historian Arthur Schlesinger Jr.,...