All night long the thunderstorm had roared over Rome, hurling lightning bolts into the city at three places. "Then on Monday morning, July 18, 1870, it abated briefly, allowing the 535 Fathers of the First Vatican Council to assemble in St. Peter's Basilica. Before them lay a historic document. In matters of faith and morals, it declared, when the Roman Pontiff speaks ex cathedra (from the chair of Peter, i.e., by virtue of his office) to the universal church, he is incapable of error.
The heavens broke open again as the roll call began. A window shattered almost directly over the pontifical...