But after this investigation of his assertions, as if his object were to swell his book by many words, he repeats, in different language, the same charges which we have examined a little ago, saying: “By far the most silly thing is the distribution of the creation of the world over certain days, before days existed: for, as the heaven was not yet created, nor the foundation of the earth yet laid, nor the sun yet revolving, how could there be days?” Now, what difference is there between these words and the following: “Moreover, taking and looking at these things from the beginning, would it not be absurd in the first and greatest God to issue the command, Let this (first thing) come into existence, and this second thing, and this (third); and after accomplishing so much on the first day, to do so much more again on the second, and third, and fourth, and fifth, and sixth?”
We answered to the best of our ability this objection to God's “commanding this first, second, and third thing to be created,” when we quoted the words, “He said, and it was done; He commanded, and all things stood fast;” remarking that the immediate Creator, and, as it were, very Maker of the world was the Word, the Son of God; while the Father of the Word, by commanding His own Son— the Word— to create the world, is primarily Creator. And with regard to the creation of the light upon the first day, and of the firmament upon the second, and of the gathering together of the waters that are under the heaven into their several reservoirs on the third (the earth thus causing to sprout forth those (fruits) which are under the control of nature alone), and of the (great) lights and stars upon the fourth, and of aquatic animals upon the fifth, and of land animals and man upon the sixth, we have treated to the best of our ability in our notes upon Genesis, as well as in the foregoing pages, when we found fault with those who, taking the words in their apparent signification, said that the time of six days was occupied in the creation of the world, and quoted the words: “These are the generations of the heavens and of the earth when they were created, in the day that the Lord God made the earth and the heavens.”
Source: Against Celsus (New Advent)