The concept of efficient causation originates with Aristotle, who states that the types of cause include ‘the primary source of the change or rest’. For Medieval Aristotelians, the scope of efficient causality includes creative acts. The Islamic philosopher Avicenna is an important contributor to this conceptual change. In his Metaphysics, Avicenna defines the efficient cause or agent as that which gives being to something distinct from itself. As previous studies of Avicenna's ‘metaphysical’ conception of the efficient cause attest, it takes (...) God as a model agent. This essay considers whether Avicenna's ‘metaphysical’ conception of the efficient cause applies to natural agents. It ultimately argues that Avicenna offers a unified view of the efficient cause, which includes both divine and natural agents. On this view, an efficient cause gives being to another and is simultaneous with its effect. While Avicenna's defence of this view is an important chapter in the history of the concept of the efficient cause, it is also of interest in its own right. By appeal to a version of the principle of sufficient reason, it challenges a widespread view that causes are temporally prior to their effects. (shrink)