In the 1880's, Pope Leo XIII had just finished celebrating Mass, he had a vision and heard two voices, that of God and of Satan. Satan boasted to God that he could "destroy the church" but asked God for 100 years and more power to do so. God responded, permitting it. After the vision, Pope Leo XIII immediately composed the Prayer to St. Michael the Archangel and decreed that it be said after Masses throughout the world.