books.google.com - 1891. Veteran scholar Sir William Muir's history of the Caliphate. A Caliph is the spiritual head and temporal ruler of the Islamic state. In principle, Islam is theocratic: when Muhammad the Prophet died, a caliph (successor) was chosen to rule in his place. The caliph had temporal and spiritual authority...http://books.google.com/books/about/The_Caliphate.html?id=DYx7LB3k7tIC&utm_source=gb-gplus-shareThe Caliphate
