His immortality may be of a scandalous variety, but the fascination still exerted by Donatien Alphonse Franois de Sade (1740-1814) is evidenced in this, the third biography of the man to appear in a scant six months. Francine du Plessix Gray (At Home with the Marquis de Sade) and Laurence Bongie (Sade: A Biographical Essay) take arguably more original approaches, but American academic Neil Schaeffer's thorough, carefully researched and argued book is more likely to appeal to the general reader who knows little of Sade beyond the perversion to which he gave his name. In fact, Schaeffer contends, the marquis was hardly a textbook sadist: he liked to be beaten at least as much as he enjoyed inflicting pain, which was a pastime he pursued primarily in his books' scatological fantasies. The author generally attempts to temper Sade's dreadful reputation, placing his escapades with prostitutes and menservants in the European tradition of aristocratic libertinism and pointing up the witty irony as well as the obscenities in works like The 120 Days of Sodom ("the most radical novel ever written"). It's not exactly a pretty picture, but Schaeffer makes a plausible case that the man imprisoned by both royal and revolutionary regimes posed more danger through his unfettered imaginings than through anything he actually did