Genesis 1:14-16 (KJV)
God Creates the Seasons
14 And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:
15 And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
16 And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
Genesis 8:20-22
The Cycles of Earth
20 Then Noah built an altar to the Lord and, taking some of all the clean animals and clean birds, he sacrificed burnt offerings on it. 21 The Lord smelled the pleasing aroma and said in his heart: “Never again will I curse the ground because of humans, even though every inclination of the human heart is evil from childhood. And never again will I destroy all living creatures, as I have done.
22 “As long as the earth endures,
seedtime and harvest,
cold and heat,
summer and winter,
day and night
will never cease.”
Exodus 20:8-11
God Creates the Week
8 “Remember the Sabbath day by keeping it holy. 9 Six days you shall labor and do all your work, 10 but the seventh day is a sabbath to the Lord your God. On it you shall not do any work, neither you, nor your son or daughter, nor your male or female servant, nor your animals, nor any foreigner residing in your towns. 11 For in six days the Lord made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy.
Mark 2:27-28
The Sabbath Was Made for Man
27 Then he said to them, "The Sabbath was made for man, not man for the Sabbath. 28 So the Son of Man is Lord even of the Sabbath."
When we open the Bible and start reading Genesis, we see that God created a seven day week, and different cycles in nature...The sun rises every morning and we have our days...The sun sets each evening and we have our nights...The moon goes through its cycles and phases...We are given six days to work and labor and God gives us a seventh day as a Sabbath Day for the LORD...Seven days make up our week...
The is proof man has body cycles and it is best for him and his well being over a seven day cycle...There are books about this mysterious seven day cycle and one of them is by Susan Perry and Jim Dawson called the The Secrets our Body Clocks Reveal...These authors say “At first glance, it might seem that weekly rhythms developed in response to the seven day week imposed by human culture thousands of years ago...However, this theory doesn't hold once you realize that plants, insects, and animals other than humans also have weekly cycles. . . . Biology, therefore, not culture, is probably at the source of our seven day week.”...Chronobiology is a scientific field of biology that studies the cycles and periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms...Dr. Franz Halberg is the father of chronobiology...He states “that body rhythms of about seven days, far from being passively driven by the social cycle of the calendar week, are innate, autonomous, and perhaps the reason why the calendar week arose in the first place…These circaseptan, or about weekly, rhythms are one of the major surprises turned up by modern chronobiology...Fifteen years ago, few scientists would have expected that seven day biological cycles would prove to be so widespread and so long established in the living world...They are of very ancient origin, appearing in primitive one-celled organisms, and are thought to be present even in bacteria, the simplest form of life now existing.”...
I would say that God is the source of the seven day week and the purpose of these seven day and other cycles...God knew and finely tuned the seven day weekly cycle for man...During His Creation Process He knew what was best for man and the other living things...He knows the seven day week is best for man, and that maybe why Jesus said the Sabbath was made for man, and not man for the Sabbath...The seven day week is best for man...
The Jewish people took up the seven day week from God's Creation and Genesis...Other people and countries took up three, four, eight, ten and different day weeks...The Roman Empire were using an eight day week...The Roman Emperor Constantine, had the seven-day week adopted for the Roman calendar in 321 a.d....Over time all cultures went to a seven day week...There must be a reason all cultures figured out that the seven day week cycle was the one best suited for man...
The whole world is now on the seven day week as God created it...When God had Noah build the Ark for the Great Flood, everything was destroyed...After the Great Flood God talks about these cycles on earth...God promised after the flood never to destroy all the living creatures again...He stated as long as the earth endures, seedtime and harvest, cold and heat, summer and winter, day and night will never cease...These cycles of nature will remain intact, as long as the earth endures...These cycles will stay in force and in tune for man...