“The highest light is God, unapproachable and ineffable, neither grasped by the mind nor expressed in language. It illumines every reason-endowed nature. It is to intelligible realities what the sun is to sense-perceptible realities. To the extent that we are purified it appears, to the extent that it appears it is loved, to the extent that it is loved it is again known. It both contemplates and comprehends itself and is poured out but a little to those outside itself. I speak of the light contemplated in the Father and Son and Holy Spirit, whose wealth is the confluence and the leaping forth of this radiance.”

-St. Gregory of Nazianzus (The Theologian), Oration 40, on Baptism