The thing is it's completely non-existent in nature. Not to get too into the Naturalistic Fallacy, but we're biological organisms that evolved in nature and hav

The thing is it's completely non-existent in nature. Not to get too into the Naturalistic Fallacy, but we're biological organisms that evolved in nature and have acclimated through evolution to it the things that do exist. That is we have a circadian rhythm, because for millions of years we couldn't see much at night, so we just went to sleep. And all sorts of animals including us start getting frisky in spring because it means resources are about to become abundant so it's a good time to copy ourselves. Even women's menstrual cycles are roughly equivalent to the lunar month. But a 7 day period? Only exists in society because of - essentially - the bible. In nature (on Earth) there are days, years, months, seasons, but that's really it. Even an hour is an arbitrary amount of time in a day (the length of which actually varies anyway!).