Nigel, which Christian sects observe Saturday as a day of rest? Sunday is all I am familiar with.

According to one of the websites, the steady rotation of seven day weeks has contnued for thousands of years, uninterrupted by calendar changes, extra leap year days etc. And we've been in sync for ages too, all the Sundays acrossa huge area match up. Nice thought.Wherever you are, Muslims have Friday, Jews have Saturday and Christians have Sunday.All goes a bit wacky at the InternationalDate Line, but basically Europe andbig chunks of Asia have been perfectly synchronised for a long time. With no organisation, either. It just started somewhere,spread out and stayed that way. Perhaps with the spread of agriculture and the Indo-European language? (That's a wild guess. The Jews weren't Indo-Europeans, nor were the Arabs).