This day is mentioned because of the chains in which St. Peter was chained by the wicked Herod and who fell from him when the angel appeared to him in prison (Acts 12: 7). These chains were kept by the Christians both for the memory of the great apostle and for their healing power, because many sick people were healed by touching them (as from the shirt of the apostle Paul; Acts 19:12). The patriarch of Jerusalem, St. Juvenal, gave these chains to Empress Eudocia, the persecuted wife of Emperor Theodosius the Younger, and she halved them and sent one half to the church of the Holy Apostles in Constantinople, and the other to her daughter, Eric. of Valentine in Rome. Eudoxia built a church for the holy apostle Peter and placed in it the chains along with those in which the apostle was chained before being found dead by Emperor Nero.