Well, with all due respect to St. Augustine, that isn’t my view. Science has told me for years that eggs were bad for my health, that fat makes people fat, and on and on, and then comes the refutation. I don’t think we should look to outside influences or explanations to try and figure out what’s clear in Scripture.
The Hebrew word “yom” used for the days of creation is used many times outside of Genesis, each time to describe a 24-hour day with evening and night, as in Genesis.
This isn’t the first time I’ve seen the argument that the days couldn’t be literal days because of the 4th-day sun creation. But all that’s necessary for day and night is light and earth rotation, and you’ll note that God created light on the first day. What the nature of that light is, we don’t know, but clearly it was sufficient. Also, remember that Revelation says there will be no sun in the Holy City, because God’s glory will be all the light that’s needed.
I very much disagree with Augustine’s claim that anyone who believes in the six day creation is “speaking idiotically.” As Martin Luther said on the subject, back when some church leaders believed that six days had to mean not millions of years, but an instant, “Grant the Holy Spirit the honor of being more learned than you are.”
It seems to me that the natural laws that God maintains, and through which we understand Creation (His other book), indicate that the earth is billions of years old. If so, Genesis must be metaphorical, with regard to the six days of Creation. Such a position is logically coherent.
Alternatively, if Creation was literally of six days duration, then God would have had to have created the world in some kind of miraculous manner (possible), but this divine Action would simultaneously give the appearance of the world being millions of years old. This would make God deceptive, which is logically impossible.