Augustine of Hippo
It is well-known that He who brought all things into existence did so as Creator; for through the Word all things came to be. (John 1:3) Regarding Him who achieved redemption upon the earth, it is proclaimed, "To you belongs the night." We must grasp something intrinsic to the very redemption He fulfilled in that earthly realm. Your own day. Who are these? The spiritual. And to You belongs the night. Who are these? The fleshly... You have perfected the sun and the moon: the sun representing the spiritual individuals, and the moon representing those of the flesh. While one remains in a carnal state, may he not be abandoned, and may he also strive for perfection. The sun resembles a wise person; the moon, a foolish person: yet You have not cast aside any.
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For it is written, "The wise man endures like the sun, but the foolish man changes like the moon." (Sirach 27:11) What then does this imply? Because the sun endures, meaning the wise man persists as the sun does, while the foolish one alters as the moon does, can one who is still carnal and lacking wisdom be disregarded? And where is the truth in what the apostle stated, ‘I am a debtor to both the wise and the unwise’? (Rom. 1:14)