Having unraveled the mysteries of Washington in his classic best-seller Parliament of Whores and the mysteries of economics in Eat the Rich, one of our shrewdest and most mordant foreign correspondents now turns his attention to what is these days the ultimate mystery — America’s foreign policy.Although he has written about foreigners and foreign affairs for years, P.J. O’Rourke has, like most Americans, never really thought about foreign policy. Just as a dog owner doesn&