יְהִ֣י אֹ֑ור וַֽיְהִי־אֹֽור
"Exist, Light!" And light happened.
The ability to make something happen is what defines free will. With God, there is no other determining factors. With mankind, our creativity is limited. The best analogy may be telling a story from memory. It may be true, or just imaginary.
The word אוֹר (aur) is light as it exists and will be set apart by the name "day". Because of this, it comes as a symbol for righteousness and holiness. At its inception it seems to have been the point at which electromagnetic energy reached the visible spectrum necessary for life on the earth. This event happened all across the surface of the "water universe".