Following after brilliant authoritarian Pope Pius XII and good-humored Pope John XXIII, Pope Paul VI seemed hesitant, anxious, even tormented. Yet the impact of his fifteen-year-long papacy was colossal: not a single aspect of Church life was left untouched in the whirlwind of change unleashed by the Ecumenical Council he guided and sought to implement. Who was this man, Giovanni Battista Montini (1897-1978), who so altered the face, the voice,...