Regarding the writings of Isaac, to date, The Mystic Treatises, is perhaps one of, if not the most important work of Isaac of Nineveh. It should be pointed out, early on, that the overriding theme of this work was for one to achieve the attainment of God’s love, the consummate union between man and God. To achieve this ecstasy, an aspirant had to acquire a spiritual, rather than an intellectual, knowledge since he should mentally dismiss much of the world. The Mystic Treatises proposes a way using the three stages, proposed by Plotinus of repentance, purification and illumination, which have also been designated the physical, psychic and spiritual levels of man. It should, however, also be quickly pointed out that Isaac did not organize his thoughts systematically, for he intertwined the three stages, with an overall progression.
These three being: Repentance, Purification and Illumination. In time, some will set the three as Purification, Illumination, and Unification.