 The action of the First Cause must therefore be conceived as exempt from any mediation. Nothing (neither a matter, nor an act of will, nor even time) can be inserted between the Principle and Its effect (see also Ḥudūd: 42–43). An image often occurs in Avicenna’s writings: the causality of the First Principle is similar to that of the hand that moves the key in the lock of a door: the movement of the hand and that of the key—respectively the cause and the effect—are simultaneous, and yet one is prior to the other. Priority is essential, not temporal (Ilāhiyyāt, IV, 1, 165).