Theocracy, from Greek roots meaning rule of God, names a system in which political authority is exercised in the name of, and is understood to derive its legitimacy directly from, a deity or divine law, rather than from popular consent, hereditary right treated as a purely secular institution, or a constitution grounded in reason alone.
The term was coined by the first century Jewish historian Josephus to describe the constitution he attributed to Moses, in which the Israelite polity had no human king but was governed through priests interpreting divine law, a usage that already shows theocracy functioning as an ideal type more than a description of any single, stable form of government. Historical examples cluster around a smaller set of real cases than the word's broad currency might suggest: Calvin's Geneva, various Anabaptist and Puritan settlements, the Islamic caliphate in its early centuries, and the Dalai Lama's pre-1950s government of Tibet are among the cases most often cited, each combining religious and political authority in ways that differ substantially from one another despite sharing the label. Josephus himself contrasted this constitution favorably with monarchy, aristocracy and democracy alike, presenting rule by priests interpreting divine law as superior to all three conventional Greek categories of government.