The Pope, the Kings and the People, by William Arthur traces the history of Vaticanism from 1864 through 1869. The sources of the information contained in this work are, 1. Official documents; 2. Histories having the sanction of the Pope or of bishops; 3. Scholastic works of the present pontificate, and of recognized authority; 4. Periodicals and journals, avowed organs of the Vatican or of its policy, with books and pamphlets by bishops and other Ultramontane writers; 5. The writings of Liberal Catholics.