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.
Repentance was to be attained through ascetic practices and solitude. Vigils, mortification and fasting were advocated since only the anchoritic life could combat the distractions which were produced by man's affections. In this capacity, solitude became the prime means of overcoming the distractions of these affections, for it fostered concentration on God through prayer. The writers contained in the Philokalia support this measure.
By his purification, the original, divine nature of man was revealed and culminated in his illumination. This attainment of spirituality was indicated by various signs of 'grace' during prayer. In such a state of ecstasy, "a fervent heat burns in the heart and unspeakable joy arises in the soul. Further sweet tears moisten the cheeks; spiritual exaltation makes the mind drunk; ineffable consolations are received by the soul; hope supports the heart and strengthens it. Then it is to him as if he dwelled in heaven" At this stage, paradoxically, man passed beyond prayer.
All these issues and more are discussed repeatedly within this book. To date, there is no greater effort than this particular publication concerning this work. This publication has completely reworked all phases of editorial and background concerning this text.