Theurgy describes the practice of rituals performed with the intention of invoking the action or presence of one or more gods, especially with the goal of uniting with the divine. Theurgy means ‘divine-working’.
The source of Western theurgy can be found in the philosophy of late Neoplatonists, where the spiritual Universe is regarded as a series of emanations from the One. From the One emanated the Divine Mind and in turn from the Divine Mind emanated the World Soul. Neoplatonists insisted that the One is absolutely transcendent and in the emanations nothing of the higher was lost or transmitted to the lower, which remained unchanged by the lower emanations.
Plotinus urged contemplations for those who wished to perform theurgy, the goal of which was to reunite with The Divine. Therefore, his school resembles a school of meditation or contemplation. Iamblichus of Calcis, a student of Porphyry (who was himself a student of Plotinus) taught a more ritualized method of theurgy that involved invocation and religious, as well as magical, ritual. Iamblichus believed theurgy was an imitation of the gods that endowed embodied souls with the divine responsibility of creating and preserving the cosmos.
Iamblichus’ analysis was that the transcendent cannot be grasped with mental contemplation because the transcendent is supra-rational. Theurgy is a series of rituals and operations aimed at recovering the transcendent essence by retracing the divine ‘signatures’ through the layers of being.