The table below represents the arrangement that Walton sees in the six days of Creation. For those of you who are aware of the Literary Framework interpretation of this chapter, you'll see some basic similarities between the two.
|1||Time||4||Sun and Moon|
|2||Weather||5||Fish and Birds|
|3||Food||6||Animals and Humans|
On the first day, God created light and separated it from darkness. He called the light "Day" and the darkness "Night". He is clearly establishing the function of time on the first day.
On the second day God created something called an expanse, or a firmament, which the ancients believed to be a material object that held back the waters in the sky. The expanse had windows and doors in it that allowed rain to come through in season. We can understand this today as God establishing the function of weather.
On the third day God gathered the lower waters so that dry ground would appear, and out of that dry ground grew vegetation. In other words, he created the function of agriculture, or food.
Time, weather, and food are the crucial and unique elements required to sustain life on earth. They are the ordering principles of existence. So on the first three days God is creating the fundamental functions of existence.
On the fourth day God creates the sun and moon to govern time. On the fifth day God creates fish and birds, not to govern weather, but to populate the spheres of sky and sea. He also gives them a function: Be fruitful and multiply. Likewise, on the sixth day he creates animals, not to govern the land, but to populate it with the same function: Be fruitful and multiply. The function of the beasts is life.
This, of course, brings us to humans. But that's such a big topic that it deserves its own post.