Then He followed it with what He made a reason for the perfection of action and the ripening of the fruits that are watered by the water [that comes] from the sky and that springs from the earth. He said: "And He has subjected to you the sun and the moon" while they are "constantly moving," meaning in their course and their illumination and what arises from them of benefits in cooking and ripening in minerals, plants, and animals. Al-Rummani said: 'The constant movement is the passage of something in action according to a customary manner in it.' Then He mentioned what arises from the existence of the sun and its absence, saying: "And He has subjected to you the night," meaning that which the moon is a sign of, "and the day," meaning that which the sun is a sign of. Each of them exists after its passing, and if one of them were eternal, the situation would be disrupted due to the absence of plants and animals, just as it is in a place where the sun does not set in the south and where it does not rise in the north.