In summarizing the themes of this book: "The... Eastern Christian themes [exemplified by the writings of Pseudo-Macarius] can be seen in Upham's Treatise on Divine Union. In this volume he analyzes carefully the origins, grounds and goals of the relationship between God and humans as well as the practices which may result in the improvement of that relationship. The journey, or goal of all human spirituality, he affirms, is the reestablishment of the perfect union with God that was broken when humans, through their free will, decided not to conform to the will of God. Every aspect of life, has a bearing on spirituality. It is through prayer and total 'abandonment' of ourselves for God that we move toward the goal."
I also see essence of Pseudo Dionysius with the first part of this work. This particular treatise is a essential key to unlocking the subject matter St John of the Cross lays down in his work(s) "Ascent of Mount Carmel and, A Dark Night of the Soul."
