Icon of the Transfiguration
Early Alexandrian tradition
According to Origen (184/185–253/254AD) and the Alexandrian theology, theoria is the knowledge of God in creation and of sensible things, and thus their contemplation intellectually (150–400AD) (see Clement of Alexandria, and Evagrius Ponticus). This knowledge and contemplation leads to communion with God akin to Divine Providence.
St. Macarius of Egypt
In the theological tradition of St. Macarius of Egypt (ca. 300–391AD), theoria is the point of interaction between God and the human in the heart of the person, manifesting spiritual gifts to the human heart.
The highest form of contemplation originates in the heart (see agape), a higher form of contemplation than that of the intellect. The concept that theoria is allotted to each unique individual by their capacity to comprehend God is consistent. This is also the tradition of theoria, as taught by St. Symeon the New Theologian (949–1022AD), that one cannot be a theologian unless one sees the hypostases of God or the uncreated light. This experience cultivates humility, meekness and the love of the human race that the Triune God has created. This invisible fire in the heart for humanity is manifest in absolute kindness and love for one's neighbor akin to selfless humility, agape or love, growing from mortification, kenosis, or epiclesis. This agape, or holy fire, is the essence of Orthodoxy.
In the Cappadocian school of thought (Saint Basil, Saint Gregory of Nyssa, and Saint Gregory Nazianzus) (350–400AD), theoria is the experience of the highest or absolute truth, realized by complete union with God. It is entering the 'Cloud of Unknowing', which is beyond rational understanding, and can be embraced only in love of God (Agape or Awe). The Cappadocian fathers went beyond the intellectual contemplation of the Alexandrian fathers. This was to begin with the seminal work Philokalia, which, through hesychasm, leads to Phronema and finally theosis, which is validated by theoria. One must move beyond gnosis to faith (meta-gnosis). Through ignorance, one moves beyond knowledge and being, this contemplation being theoria. In this tradition, theoria means understanding that the Uncreated cannot be grasped by the logical or rational mind, but only by the whole person (unity of heart and mind); this perception is that of the nous. God was knowable in his manifestations, but ultimately, one must transcend knowledge or gnosis, since knowledge is based on reflection, and because gnosis is limited and can become a barrier between man and God (as an idolatry). If one wishes to commune with God, one must enter into the Divine filial relation with God the Father through Jesus Christ, one in ousia with the Father, which results in pure faith without any preconceived notions of God. At this point, one can commune with God just as Moses did. Gregory of Nyssa presented as the culmination of the Christian religion the contemplation of the divine Being and its eternal Will.
Pseudo-Dionysius the Areopagite's apophaticism
Pseudo-Dionysius the Areopagite (5th to early 6th century; writing before 532), himself influenced by the Neoplatonic philosopher Proclus, had a strong impact on Christian thought and practice, both east and west. Theoria is the main theme of Dionysius’ work called "The Mystical Theology". In chapter 1, Dionysius says that God dwells in divine darkness i.e. God is unknowable through sense and reason. Therefore, a person must leave behind the activity of sense and reason and enter into spiritual union with God. Through spiritual union with God (theosis), the mystic is granted theoria and through this vision is ultimately given knowledge of God. In the tradition of Dionysus the Areopagite, theoria is the lifting up of the individual out of time, space and created being, while the Triune God reaches down, or descends, to the hesychast. This process is also known as ekstasis ("mystical ecstasy").
While theoria is possible through prayer, it is attained in a perfect way through the Eucharist. Perfect vision of the deity, perceptible in its uncreated light, is the "mystery of the eighth day". The eighth day is the day of the Eucharist but it also has an eschatological dimension as it is the day outside of the week i.e. beyond time. It is the start of a new eon in human history. Through the Eucharist people experience the eternity of God who transcends time and space.
The Dionysian writings and their mystical teaching were universally accepted throughout the East, amongst both Chalcedonians and non-Chalcedonians. St. Gregory Palamas, for example, in referring to these writings, calls the author, "an unerring beholder of divine things".
In western Christianity Dionysius's "via negativa" was particularly influential in the fourteenth and fifteenth centuries, on western mystics such as Marguerite Porete, Meister Eckhart, John Tauler, Jan van Ruusbroec, the author of The Cloud of Unknowing (who made an expanded Middle English translation of Dionysius' Mystical Theology), Jean Gerson, Nicholas of Cusa, Denys the Carthusian, Julian of Norwich and
Harphius Herp. His influence can also be traced in the Spanish Carmelite thought of the sixteenth century among Teresa of Avila and John of the Cross.