For in six days the LORD made heaven and earth,
the sea, and all that in them is,
and rested the seventh day:
wherefore the LORD blessed the sabbath day,
and hallowed it.
Exodus 20:11
"God establishes form—or realms—in the first three days, and creates inhabitants for each of the formed realms on days four through six. 
The following are proposed as parallel:
* light of day 1/light-bearers of day 4;
* creation of the firmament of day 2/living creatures of the waters of day 5;
* dry land of day 3/inhabitants of the earth of day 6.
The symbolic framework hypothesis views this literary structure as a means by which the author accentuates the climactic point of the structure.
@ This climax may be the sixth day, the crown of creation—man made in the divine image.
@ This particular view also acknowledges the importance of the Sabbath, often considered to be written to validate Sabbath observance.
..... highlight day 7, God’s day of rest, and also the goal of creation—God’s covenant relationship with us." KC