Leupold Genesis part 25 overview of structure

But quite apart from such attempts to fit the whole creation into a pattern of our own devising it is immediately apparent that the account as a whole proceeds from the lower to the higher, providing first the basic essentials for existence as well as for plant and for animal life, then running to a climax in the creation of man for whose well-being and well-ordered existence all previous steps in creation provide the adequate setting. So the account abundantly displays that God is a God of order. The very general formula devised by Driver (quoted by Skinner) is as satisfactory as any: "The first three days are days of preparation, the next three are days of accomplishment."