It is possible to summarize the Creation story as a set of answers to some basic questions. Why is there something rather than nothing? Because in the beginning God created. Why is there what there is and not something else? Because he created heavens, earth, sea, land, stars, moon, sun, plants, animals, and humans. And why do we have the Sabbath? Because when God was done creating he rested. At this point, though, we circle back on ourselves. Why did God rest? Because he wanted to create the Sabbath. We still don’t know why the Sabbath should be a part of Creation...
It begins as simply as a folktale and ends with the magnificence of church-organ Bach. Along the way, it offers a tantalizing glimpse of ancient science. P (The Priestly Author) doesn’t just tie the material world to the creativity of his First Cause; he categorizes God’s creations. There are sea and sky and land; fish and birds and animals; beasts that run wild, beasts that can be domesticated, and beasts that crawl; and, of course, humans. P doesn’t limit himself to the physical, either. His God creates the temporal, too, though he doesn’t so much call forth the units of time as divide them one from the other. Light he creates, but then he divides day from night, allotting much light to day and a lesser amount to night. Evening is winnowed from morning. There is one day, then two days, then three, then six.
The most remarkable feature of P’s protoscientific narrative, though, is that it leads us with every weapon at the poet’s disposal—rhythm, repetition, parallelism—toward its conclusion: the seventh and final day. This is no accident. P is working out the details of a monotheistic cosmos, and the Sabbath would seem to be an essential element of it. Behold creation in all its magnificence, P appears to be saying. This can’t be the work of some squabbling, inconsistent, all-too-human gods. It can only be the work of the one God who dwells beyond time and space, light and matter. The Sabbath is that dwelling.
Shulevitz, Judith (2010-03-18). The Sabbath World: Glimpses of a Different Order of Time. Random House, Inc.. Kindle Edition.