THE POWER of the apocalyptic has never ceased to tease the American mind. A glance through the nation's past reveals a tenacious flirtation with conspiratorial fantasies and one-idea men. This rage for machinations is all the more curious considering the many generations that the U.S. basked in the security of splendid isolation. Perhaps the lack of external nemeses coaxed the darker corners of the American imagination into a twitchy suspicion of native demons. Not even our textbook heroes have evaded the paranoiac's gaze. The post-Revolutionary Federalist press massaged Jefferson's private Deism into a menacing infidelism; the Anti-Masonic Party denounced Andrew Jackson's fraternal ties; John Birch Society founder Robert Welch called Eisenhower a possible "conscious, dedicated agent of Communist Conspiracy." Today, the chase to stamp out villainy spins with the velocity of 24/7 news cycles.