Lourie does full justice to a life that could not be more engrossing. The socially introverted son of Moscow intelligentsia, Andrei Sakharov became a star physics pupil, then chief architect of the Soviet Union's first thermonuclear device, and later on a dissident and target of KGB ire -- and finally the moral conscience of a democratically awakening Russia. This grand curve unfolds amid the humanizing detail of his boyhood explorations, young marriage, family relations, friendships, and intellectual eccentricities. (Like his hero Pushkin, he would exclaim at the point of an intellectual breakthrough, "O Pushkin, you son of a bitch, you!") The evolution from a politically passive scientist to a lonely figure holding sidewalk vigils outside kangaroo courtrooms is almost unfathomable for a non-Russian. Lourie, however, makes it comprehensible, not least by painting with an artist's spare, deft strokes this transcendent figure into the history of his day.