While we cannot know God in His essence (God in Himself), we can know Him in his energies (the work of God’s grace in our lives, and who God is in relation to the creation and mankind). Both essence and energies are fully God. Therefore, when interacting with God’s energies, we interact with the uncreated God Himself, while His essence still remains unknowable and unreachable. Imagine that God is the sun. We all experience the power and energy of the sun every day. We experience its warmth and light (both of which are energies) through the rays that shine down on us. These rays don’t give us a mere impression of what the sun is; they are not a substitute for the sun, nor do they merely illustrate what the sun is like. They are a real participation in the very energies of the sun itself. In other words, by our contact with the sun’s rays, real changes occur in our human chemistry. At the same time, however, we cannot participate in or experience the essence of the sun. If we tried to approach the essence of the sun, it would overwhelm and annihilate us.
Like the sun, we can experience God in His energies, while His divine essence remains unknowable and unreachable.
So it is with God and His grace. God’s grace is not a participation in the transcendent and unknowable essence of God. However, it is a real experience of God through His divine energies. And it is these energies that were experienced:
in the burning bush (Ex. 3:2) and on Mount Sinai (Ex. 24:16)
by the priests in the ark of the tabernacle of testimony (1 Kings 8:10)
as a cloud and pillar of fire in the wilderness (Ex. 13:21)
upon the dedication of the Jerusalem temple (2 Chronicles 7:1)
by Saul when a blinding light knocked him from his horse (Acts 9:3-4)
by Peter, James, and John on Mount Tabor during the Lord’s Transfiguration (Matt. 17)
And on many other occasions
In fact, according to Saint Gregory Palamas and many other theologians, the Apostles actually witnessed the uncreated light of God; and it is possible for others to see that same uncreated light of God with the help of repentance, spiritual discipline and contemplative prayer.
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An excellent resource for a florilegium of patristics on the topic is our friend Ubi Petrus: These can be found in two parts here Part 1 Essence – Energies Distinction in the Church Fathers – Ubi Petrus Ibi Ecclesia Part 2 Essence – Energies Distinction in the Church Fathers – Part II – Ubi Petrus Ibi Ecclesia --------------------------------------------
This article can be read in greater detail at the church site for the St John the Evangelist parish: