Angelo Guiseppe Roncalli was an unexpected choice to follow the ultra conservative Pope Pius XII in 1958. At seventy-six years old, 'a fat old man with twinkling eyes and a seductively resonant voice', neither a well-known public figure nor a highly trained theologian, he was at first regarded as a transitional pope. During his brief but unforgettable reign as Pope John XXIII, however, he astonished the world with the seminal and unprecedented change he brought about in the Catholic Church, and in particular with his concern for the fundamental plight of humankind. Pope John XXIII was unlike any other pope. To understand his extraordinary impact, which still resonates today, and his crucial importance to the world's one billion Catholics, Thomas Cahill opens this biography with a concise but sweeping history of the Catholic Church and the papacy, culminating in Pope John XXIII's reign in the mid-twentieth century. In rich, impassioned prose, Cahill follows the pontiff's life from his peasant roots to his establishment of the landmark Second Vatican Council, with its emphasis on worldwide social justice, which marked the beginning of a true shift in the Catholic Church and its relationship to the modern world. In a biography that will captivate Catholics and non-Catholics alike, Cahill's signature blend of imagination, interpretative insight and scholarship mirrors Pope John's own intuition, spontaneity and all-embracing vision.