The authority of Iranian patrimonial monarchs generally is perceived to be arbitrary. A. Reza Sheikholeslami, making extensive use of the Iranian government archives for the first time, shows that in the case of Nasir al-Din Shah, 1848-1896, the king's authority was more complex. Its exercise varied over time, but most importantly the nature of authority depended on the context. The royal authority was often restrained by the tradition in which it was rooted. Personalism was mitigated by precedent which created its own norms. Yet also, as a result of inspiration from Western models of authority, the king's authority was hierarchically absolute over the formal organizations he established. Here patrimonial authority reigned supreme. The author concludes that tyranny may spring from the juxtaposition of modern institutional structures, devoid of procedures, against weakened traditional modes of authority.