The author examines historical and archeological evidence, evidence from pagan literature and other non-theological sources to prove the primacy of the Roman Catholic Church. The resulting picture spans over two millennia of history. In a rigorously scientific way, Guarduci gives evidence of certain concatenations of events that, as if obeying a mysterious design, tend to confirm the primacy of the Church of Rome, the ancient universality of which survives to this day in the spiritual primacy of the Roman "Catholic"–that is, Universal–Church. And this survival is guaranteed down through the centuries by the presence in the Vatican of the authentic earthly remains of the Apostle whom Christ selected as his vicar on earth. Paper.