This practice dates to 321 CE, when the Emperor Constantine, a new convert to Christianity, ordered it as a day of rest throughout the Roman Empire. Unfortunately, in Christianity that was the beginning of a long tradition of enforced church attendance, and a rather dreary legalism designed to keep people away from the sensual pleasures, which naturally arise when we are well rested. We know that all of nature moves in cycles of activity and rest. We have only to look at the season to see the cycles. Plants have annual resting periods when they are guided by ancient inner cues.
Plants go through two stages of dormancy.
In the first, which is called quiescence, in response to what is going on in the environment, the plant slows down. If there is less light, or there is a sudden cold snap, a plant will stop growing. But when it warms again, it will begin to grow. In the second stage of dormancy, called rest, plants seem to heed inner cues, rather than what is happening in the environment. Even in favorable conditions, some seeds will remain dormant, as though they know that they cannot grow to full maturity if they begin to grow too soon.