Ambrose of Milan, on Ps 103:19

“He hath made the moon for seasons: the sun knoweth his going down.”

“Consider that the sun, the moon and the stars, the lights of the sky which, though they shine with brilliant splendor, are yet creatures, and, whether they rise or fall in their daily performance of duty, they serve the will of the eternal Creator, bringing forth the beauty with which they are clothed and shining by day and by night. How often is the sun covered by clouds or taken from the gaze of the earth when the ray of its light is dispelled in the sky or an eclipse occurs, and as Scripture says: "The moon knows its going down." It knows when it should shine in full light or weakened light. The stars, which are engaged in service to this world's advantage, disappear when they are covered by clouds, not willingly, surely, but in hope, because they hope for gratitude for their labor from him who made them subject [to him]. Thus, they persevere for his sake, that is, for his will.”

Imported from an open dataset — not yet checked against the printed edition.