[32] Right too is his statement that “darkness was above the abyss” (Gen. 1:2). For in a sense the air is over the void, inasmuch as it has spread over and completely filled the immensity and desolation of the void, of all that reaches from the zone of the moon to us.
[33] After the kindling of the intelligible light, which preceded the sun’s creation, darkness its adversary withdrew: for God, in His perfect knowledge of their mutual contrariety and natural conflict, parted them one from another by a wall of separation. In order, therefore, to keep them from the discord arising from perpetual clash, to prevent war in place of peace prevailing and setting up disorder in an ordered universe, He not only separated light and darkness, but also placed in the intervening spaces boundary-marks, by which He held back each of their extremities: for, had they been actual neighbours, they were sure to produce confusion by engaging with intense and never-ceasing rivalry in the struggle for mastery.
[34] As it was, their assault on one another was broken and kept back by barriers set up between them. These barriers are evening and dawn. The latter, gently restraining the darkness, anticipates the sunrise with the glad tidings of its approach; while evening, supervening upon sunset, gives a gentle welcome to the oncoming mass of darkness. We must, however, place these, dawn and evening I mean, in the category of the incorporeal and intelligible: for there is in these nothing whatever patent to the senses, but they are simply models and measuring-rules and patterns and seals, all of these being incorporeal and serving for the creation of other bodies.
[35] When light had come into being, and darkness had moved out of its way and retired, and evening and dawn had been fixed as barriers in the intervals between them, as a necessary consequence a measure of time was forthwith brought about, which its Maker called Day, and not “first” day but “one,” an expression due to the uniqueness of the intelligible world, and to its having therefore a natural kinship to the number “One.”