Theurgy

Theurgy — literally 'divine work' or 'god-working' — is the practice of sacred rites, invocations, and symbols by which the soul is purified and raised toward the divine. It draws on the Chaldean Oracles, the verse revelation that the later schools treated almost as scripture, and was given its classic philosophical defense by Iamblichus in the treatise On the Mysteries.

The argument for ritual

Iamblichus argued, against Porphyry's doubts, that the human soul has fully descended into the body and so cannot lift itself back to the gods by thought alone. The gods, however, have sown divine tokens or signatures (synthemata) throughout creation — in stones, plants, names, and sounds — and through rites that use these the soul aligns itself with the powers above. Theurgy is therefore emphatically not magic that compels the gods; it is a cooperation with a grace the gods themselves extend, and its efficacy comes from them, not from the operator's will.

Its place in the tradition

This view shaped later Neoplatonism, running from Iamblichus through Proclus — who practiced the rites of many cults and held the philosopher to be priest of the whole world — down to the last pagan schools. It marks off the more devotional, sacramental strand of the tradition from the purely contemplative ascent of Plotinus, and it set a pattern that later sacramental and mystical theologies would echo.