more on Proclus' Theurgy

Studies on the 5th [fifth] and 6th [sixth] essays of Proclus' Commentary on ...
By Anne D. R. Sheppard p161 Proclus saw the traditional mystery language of Greek philosophy with the eyes of one who believed in the practice of theurgy and in the possibility of mystical experience. The metaphor therefore had a precise meaning for him and he used it in a variety of ways. In Proclus's thought everything really does reflect everything else. Like a modern structuralist he finds the same underlying pattern in the mysteries, in theurgy, in philosophy, in language, in myth, and in the world as a whole. The principles behind the use of symbola in theurgy are also the principles behind Proclus' interpretation of poetic myths and so he can transfer language from the one sphere into the other and use mystery-language to provide a terminology for allegory.

What is not in us is not on the level of our knowledge; what is not on the level of our knowledge is unknowable by our faculty of knowledge; so then the transcendent Forms are unknowable by our faculty of knowledge. They may, then, be contemplated only by divine Nous. This is so for all Forms, but especially for those that are beyond the noeric gods; for neither sense-perception, nor cognition based on opinion, nor pure reason, nor noeric cognition of our type serves to connect the soul with those Forms, but only illumination from the noeric gods renders us capable of joining ourselves to those noetic-and-noeric Forms, as I recall someone saying under divine inspiration. The nature of those Forms is, then, unknowable to us, as being superior to our intellection and to the partial conceptions of our souls. And it is for this reason, indeed, that the Socrates of the Phaedrus, as we said before, compares the contemplation of them to mystic rites and initiations and visions. -Proclus In Parm. 949, 14ff., trans. Morrow/Dillon 1987: 300. (slightly adapted). (quoted in link below)

According to Proclus, only divine Nous is capable of contemplating the Forms. Since the divine Nous is identical with the Demiurge, i.e. the Father of the universe, and since every effect strives after reversion to its cause, the human soul can contemplate the Forms if it manages to return to the Demiurge, which may be referred to as reaching the paternal harbour. The leader-gods discussed in Theol. Plat. VI play an important role in the return of the human soul, because they are the intermediate causal principles between us and the Demiurge. They are characterized by likeness, which is mirrored in all their products. This likeness that causes and products share is the basis sympatheia, the driving force behind theurgy. Proclus uses theurgical ritual, based on this sympatheia, to attract the leader-gods in order to be elevated towards the divine Nous. At least some of Proclus' hymns were part of these rituals.

R. M. van den Berg, Towards the Paternal Harbor, Proclean Theurgy and the Contemplation of the Forms.