God is not free to act; He is bound by human ethics. To be just, He must create an individual of perfect intellect and infallible morality. People are obligated to submit to this person; otherwise eternal damnation awaits them. While these claims may be interpreted as an affront to God's power, an insult to human judgement and a justification for despotism, Shi'i Muslims in the eleventh century eagerly adopted them in their attempts to forge a 'rational' religious discourse. They utilised everything from literary studies and political theory to natural philosophy and metaphysical speculation in support of this project. This book presents the contribution of al-Sharif al-Murtada (d. 1044) of Baghdad, the thinker most responsible for this irreversible change, which remains central to Imami identity. It analyses his intellectual project and establishes the dynamic context which prompted him to pour the old wine of Shi'i doctrine into the new wineskin of systematic Mu'tazili theology.