The pontificate of Leo XIII was theologically influenced by the First Vatican Council (1869–1870), which had ended only eight years earlier.
Leo XIII issued some 46 apostolic letters and encyclicals dealing with central issues in the areas of marriage and family and state and society.
He also wrote two prayers for the intercession of Michael the Archangel after he allegedly had a vision of Michael and the end times, but the story of the alleged vision may be merely apocryphal, as historians note that the story does not appear in any of his writings.

Leo XIII also approved a number of Scapulars.
In 1885, he approved the Scapular of the Holy Face, (also known as The Veronica) and elevated the Priests of the Holy Face to an archconfraternity.
He also approved the Scapular of Our Lady of Good Counsel and the Scapular of St. Joseph, both in 1893, and the Scapular of the Sacred Heart in 1900.
The pontificate of Leo XIII was theologically influenced by the First Vatican Council (1869–1870), which had ended only eight years earlier. Leo XIII issued some 46 apostolic letters and encyclicals dealing with central issues in the areas of marriage and family and state and society. He also wrote two prayers for the intercession of Michael the Archangel after he allegedly had a vision of Michael and the end times, but the story of the alleged vision may be merely apocryphal, as historians note that the story does not appear in any of his writings.
Leo XIII also approved a number of Scapulars. In 1885, he approved the Scapular of the Holy Face, (also known as The Veronica) and elevated the Priests of the Holy Face to an archconfraternity. He also approved the Scapular of Our Lady of Good Counsel and the Scapular of St. Joseph, both in 1893, and the Scapular of the Sacred Heart in 1900.
Pope Leo XIII