When Dominic was in Rome seeking papal confirmation of his Order, he had a mystical experience in which St. Peter and St. Paul played an important role. While waiting to see Honorius III, Dominic took refuge in prayer. His favorite shrine was the Vatican basilica, where, night after night, he invoked the aid of St. Peter and St. Paul. In a vision one night these two great apostolic missionaries appeared to Dominic and authorized him to preach with apostolic zeal and authenticity, symbolized by Peter’s staff and Paul’s book. They also gave him this commission: “Go and preach, for to this ministry thou art called.” Then they disappeared, replaced by an image of Dominic’s friars traveling in pairs throughout the world, preaching the Word of God to all nations. This vision became a reality, for wherever Dominic preached the people flocked to him, eager to hear his words. Within just thirty-five years of his death the Order numbered five thousand priests and two thousand other clerics and cooperator brothers.
The above excerpt is from Reflections of Dominican Spirituality: The Windows of St. Dominic Church, Washington, D.C. by Dr. Mary Moran.