Mystical theology in the Catholic Church has developed along very different lines. In the Latin tradition, Eastern mysticism is interpreted in the context of the overall development of Western mysticism, so that mysticism in the Greek Church is conceived as the necessary foundation for the flowering of mysticism in the Latin Church. In addition, the Latin tradition has two distinctive traits. First, Western mysticism is notably individualistic, understood to be perfected in the rarefied experiences of figures such as St. Francis of Assisi, St. Catherine of Siena, or St. John of the Cross. Second, the emergence of Aquinas' grand Aristotelian synthesis approximates the time of separation between the Western and Eastern Churches, so that mystical theology in the Catholic Church uses the vocabulary of Scholasticism, which almost never appears in the Greek tradition.
In the Greek tradition, on the other hand, the mysticism of the first centuries is not seen as the seed but rather as the fruit. Moreover, because the writings of the Eastern mystics are very closely interpenetrated with the exposition of early Church dogmas, mystical theology is, in effect, a species of dogmatic theology. Mystical theology in the Greek tradition is communal in the sense that it sets forth the pattern by which all individual members of the Orthodox Church are expected to grow in the mystical understanding of dogma. Lossky states the Orthodox position this way: "The eastern tradition has never made a sharp distinction between mysticism and theology; between personal experience of the divine mysteries and the dogma affirmed by the Church." Eastern mysticism also exists in the milieu of Hellenistic philosophy, specifically neo-Platonism, so that this perspective colors all Eastern mystical theology.
Besides these broad distinctions, there are very precise differences in doctrine as well, and the thoughtful reader will find enough theology in this book for unhurried, profound reflection. Subtle yet immense differences become apparent in the highly developed mystical theology that Lossky expounds as he proceeds from one topic to the next, beginning with the via negativa of Pseudo-Dionysius, moving on to nature of the Trinity, the meaning of theosis or divinization, the mystical vision of the Church, the transcendence of mystical union, and ending with the fulfillment of history in the parousia. No fast food here, just slow digestion for the theologian.
Of most importance to the Western mystical tradition is the concept of the via negativa, that God is best understood and contemplated in terms of what God is not, the negative attributes of God. What has been called the apophatic or negative theology of the Greeks has become integral to the Latin canon and is in fact fundamental to the mystical theology expounded in the writings of the master himself, St. John of the Cross. His description of the ascetical path of the soul toward God as a "dark night"--a permutation of the via negativa--has become one of the treasures of Western spiritual heritage.
The chapter I liked best was on "Uncreated Energies," the Orthodox doctrine of grace. What in the Catholic Church is conceived of as habitual and actual grace is in the Orthodox Church expressed very acutely, in my opinion, in the ancient idea of theosis or divinization. Divine energies proceed, uncreated, from the essence of God. By them we Christians participate in the divine nature and through them we are gifted with the glory of heaven. Interestingly, in this idea of "procession," neo-Platonist influence is manifest.
I also appreciated Lossky's extensive discussion of the mystical theology of St. Gregory Nazianzen, whom St. Francis de Sales frequently cites in his seventeenth-century spiritual classic, Introduction to the Devout Life. I had the opportunity to make closer acquaintance with a Greek Father who is so often well spoken of in Catholic literature.
For anyone who would like to learn about the unique character of mystical theology in the Orthodox tradition, to grasp its special contribution to the development of the Catholic tradition, as well as to gain insights into the shared origin of and doctrinal divergence between the two churches, I would venture that there is no better book.
It is important to note that Christian doctrines such as the Trinity are not spelled out as isolated abstract ideas, but instead, as they relate to humanity and the Church. All the chapters in this book are great, but of special interests are the chapters on the "Trininty", "Uncreated Energies", "Image and Likeness" and "The Way of Union." A book the enlightens and challenges not only the mind, but also the soul.