[35] But when light came, and darkness retreated and yielded to it, and boundaries were set in the space between the two, namely, evening and morning, then of necessity the measure of time was immediately perfected, which also the Creator called “day.” and He called it not “the first day,” but “one day;” and it is spoken of thus, on account of the single nature of the world perceptible only by the intellect, which has a single nature.