The doctrine of the knowledge of God is closely related in Gregory to the doctrine of the vision of God. In both doctrines the incomprehensibility of God, the impossibility to comprehend His nature and to see Him in His essence is a starting-point. ‘God’, says Gregory, ‘is light unapproachable, unceasing, which has no beginning, no cessation, which is immeasurable, always shining, thrice-resplendent: only a few can see it as it is, I think, not even a few’.[1] In other places, however, Gregory speaks of people who ‘see God with their pure eyes’.[2] The virgins who have reached the state of deification ‘see God, and God sees them, for they belong to God’.[3]

            We should note that the theme of the vision of God is a leitmotif of the entire Eastern Christian Tradition. St Irenaeus said that ‘the glory of God is the living man, and the life of man is the vision of God’.[4]

            The initial paradox of the theme of the vision of God is that, according to the biblical and patristic tradition, God is invisible in His nature and therefor any kind of vision of Him ‘as He is’ is impossible for the human person. There are, however, several qualifications to this statement. First, the invisible God becomes visible in the person of Jesus Christ: ‘No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, He hath declared Him’.[5] According to Irenaeus, ‘the Father is the invisible of the Son, and the Son is the visible of the Father’.[6] Secondly, God, Who is invisible for the human person in his fallen state, can become visible for those who have attained the state of deification and have their ‘eyes of the soul’ open.[7] Thirdly, God, Who is invisible in His essence, can reveal Himself to a human person in His energies, through which it is possible to see God.[8] Finally, God, Who is invisible for the human person in the present life, might become visible in the age to come: ‘Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when He shall appear, we shall be like Him; for we shall see Him as He is’.[9]

            According to Gregory, the vision of God is possible in the present life, even though for a very few, but it will be much fuller in the future age: 

With the help of the great books of the divine prophets

and the God-inspired disciples of Christ the Guide,

whose thought was sharpened by the resplendent Spirit

and who with their pure hearts saw the great God,-[10]

for this is the only way to receive the invisible Deity,-

with their help we came to know the divine, became illumined by God, ascending higher,

as far as it is possible for ephemeral creatures to ascend to God in this life.

For it is not easy for the eye to penetrate through a cloud,

even if the sight is very sharp. But what is more than that, is only possible for us later.

The reward for one’s desire is when one reaches the desirable.[11] 

            Therefore Gregory understands the words ‘Blessed are the pure in heart: for they shall see God’[12] as a promise that God can be seen in this life, but he emphasizes, following biblical and patristic tradition, that a fuller vision is possible only in the eschatological age to come. What is visible in the present life is only ‘a certain sketch (skiagrafia) and an outline (procharagma) of the invisible’.[13] In earthly life the human person desires to see God and to a certain degree sees Him, but a fuller vision belongs to the life after death: 

For it is said, For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known’.[14] What is our humiliation, but what great also is a promise, to know God as also we are known (by Him)! This is what Paul says, a great messenger of the truth, an instructor of pagans in faith, who... reached up to the third heaven, who saw paradise[15] and who for the sale of perfection had a desire to depart.[16] Moses also could hardly see the averted figure of God from behind the rock[17] - whatever is the meaning of ‘the averted figure’ and ‘the rock’ - and this was after he had prayed a lot and had received a promise. However, even he did not see as much as he wanted to see, for what escaped from his sight was greater than what appeared to him.[18] 

            Moses ascending Mount Sinai is, from Philo of Alexandria onwards, a traditional image of the mystic.[19] The vision of ‘the averted figure’ (opisthion) of God is allegorically interpreted in the sense that God can be seen in His energies but not in His invisible essence.[20] According to another interpretation, Moses sees God in the bodily image of the incarnate Word.[21] This interpretation is closer to Gregory.[22] He suggests that Moses could not see the invisible and ungraspable God, Who becomes ‘graspable’ (comprehensible) only because of His self-emptying: 

Had God remained in His heights,[23] had He not descended to our weakness, had He remained what He was, preserving Himself unapproachable and ungraspable, perhaps only a few people would have followed Him. I do not even know whether a few would follow Him: perhaps only one Moses, and even he up to seeing the averted figure of God. For, though he penetrated through the cloud, after having become outside bodily grossness and having reduced his senses, he could not see the subtleness and incorporeality of God - or I do not know how to name this - for he was in the body and watched with bodily eyes. However, as God empties Himself for us, as He descends,- I call self-emptying (kenosis) this sort of weakening and wearing down of glory,- so He becomes graspable.[24] 

            Speaking of the appearances of God to the Old Testament righteous people, Gregory says that not one of them could see God in His incorporeal and invisible essence. They could only see Him in human form: 

Abraham, mighty patriarch that he was, was justified by faith.[25] The sacrifice he offered was unusual in its foreshadowing of the great one to come.[26] Yet he did not see God directly. No, he gave Him food as man and was commended because his awe matched his comprehension.[27] Jacob dreamed of a lofty ladder and of angels ascending it.[28] His anointing a pillar had a hidden meaning perhaps...[29] He gave place the name ‘vision of God’[30] in honour of what he dreamed. He wrestled as man with God[31] - whatever ‘wrestling between God and man may be: the comparison of human excellence with God, perhaps?.. Yet neither he, nor any other after him... could boast this: that he had taken in the nature, the total vision, of God.[32] 

            The human person is able to sense God’s presence, to see God in certain mysterious symbols and images, to be taken in mystical rapture up to the third heaven and encounter God there; however, God remains invisible and His essence, inaccessible. Every appearance of God, as Gregory emphasizes, is only a certain degree of the presence of the One Who by His nature is greater than any of His own visible appearances. And even this presence can be unbearable for the human person; even this partial and incomplete experience of vision he is unable to express in words: 

For Elijah, so the narrative tells us, it was not the mighty wind or the earthquake but a light breeze which gave outline to the presence, but not the nature, of God.[33] ...Manoah was overwhelmed by the sight of God in a vision. ‘Wife’, he said, ‘we are lost, we have seen God’[34]- meaning with this that even a vision of God is too much for men let alone God’s nature. Peter would not let the apparition of Christ on board the boat and so bade Him depart...[35] Isaiah saw the Lord Sabaoth seated on His throne of glory, surrounded, enveloped, by six-winged Seraphim passing Him.[36] ...Ezekiel describes God’s chariot of Cherubim, the throne above them, and beyond the throne the firmament. He describes the visionary figure he saw in the firmament, certain sounds, movements, and actions too.[37] Was this a day-time appearance, the kind seen only by saints? A veridical vision of the night? I cannot say. The God of the prophets - He knows; so do the prophetically inspired. But none of those I talk of, nor any other of their sort, stood within the essential ‘basis’, as Scripture has it, ‘of the Lord’.[38] None saw, none told, of God’s nature. Had Paul been able to express the experiences gained from the third heaven,[39] and his progress, ascent, or assumption to it, we should, perhaps, have known more about God - if this really was the secret meaning of his rapture. But since they were ineffable, let them have the tribute of our silence.[40] 

            Thus, both the knowledge of God and the vision of God belong to the human person in the highest stages of his mystical progress, and even this only as far as it is possible for the human nature. The vision of God becomes possible for the one who has purified himself, has attained to deification and remains in prayer. However, the human person can only have a partial and incomplete experience of this vision: he can feel the mysterious presence of God, but God remains ungraspable, inexpressible, inaccessible and invisible.