Rev 21:23

“And in that he says that the sun is not necessary in the city, he shows, evidently, that the Creator as the immaculate light shines in the midst of it, whose brightness no mind has been able to conceive, nor tongue to tell.”

“Wishing to relieve us altogether from the changeability characteristic of the luminaries of the day and the night, and to call us to that immutable Light, it says, "[The city] had no need of the sun," nor is that city illumined by that [natural] order. Rather, it is illumined by a much superior and ineffable Light, namely, the Sun of righteousness. Speaking of him, the prophet says, "Healing is in its wings." "For he is himself the true Son and eternal life and the true light who enlightens every one coming into this world."”

“Where there is the intellectual Sun of righteousness, there is no need of perceptible illuminaries. For he is both the glory and the lamp of the city, and "the nations" of those who are being saved will walk in its light.”

“And the city had no need of the sun nor the moon to shine in it. Because the Church is not governed by the light or elements of the world, but is led by Christ, the eternal sun, through the darkness of the world.”

“For the glory of God will illuminate it. For we will enjoy the same light in the homeland by which we are now guided while walking on the way. By this same light, being shaped, we discern between good and evil, by which then, being made blessed, we will see only what is good.”

“QUESTION: And the city hath no need of the sun, nor of the moon, to shine in it. ANSWER: Because the Church is not guided by the light or elements of the world, but it is led through the darkness of the world by Christ, the eternal Sun. THERE FOLLOWS: For the glory of God will enlighten it. ANSWER: The light we shall enjoy in our fatherland is the same one by which we are now guided as we walk on the way. It is by the same light by which we have been taught to distinguish between good and evil that we shall then be made blessed and see only what is good.”

“What an image there is in these words, that the city, which has no need of a temple, has no need of the brightness of the heavenly luminaries! And what is the reason for this? Because the glory of God gives it light. The glory of God, that is, the presence of his majesty, about which it is said, "We shall see him as he is." Therefore, why would those who shall see God have need of sun or moon?”

“And the city, it says, has no need of the sun. For they enjoy the light of the divine and spiritual. For in that time the saints perceive, at the end of the spiritual things, no need of sensible light.”