A THOUSAND DAYS: JOHN F. KENNEDY IN THE WHITE HOUSE by Arthur M. Schlesinger Jr. 1,087 pages. Houghton Mifflin. $9.
Of all the Kennedy books that have cascaded from the presses in the past two years, this is the first from a professional historian. By no coincidence, it is also the best. As an ex-presidential assistant, Harvard Historian (The Age of Jackson) Arthur M. Schlesinger Jr. is not an altogether dispassionate chronicler; he makes the fatuous claim, for example, that Kennedy's legislative record was "unmatched in some respects since the days of Roosevelt." But...