GreggB says: " People start their weeks on Monday, and end it with the "Weekend". Why would the week-end be split between two weeks?" you realize that "weekend" is for the English speaking people, "fin de semana" for us begins Friday afternoon (you can go to bed late Friday and Saturday) and Sunday is the day when you go (went, society is changing) to church, you wanted to start the week in a good way, you can't count Sunday as leisure because it was the day when you came to a social compromise like a baptism or a wedding and went to home early because you had to shine your shoes and get your things ready for Monday. Religion has shaped many things in society, and traditions is a big part of that, in religion you have many reasons for what we do now.
I love this kind of discussions because they are the perfect example of the different maps we people have, usually we think we are right and we are just discussing different views of the world, (the world see it through different color glasses said a teacher).
Well is fun to a point, in real world some people try to force their world vision to the rest and that's how wars begins, everybody say "hey, I'm right. YOU don't understand" "this is the right way to do things" "you must be crazy if you think/act like that" but that is for another forum

Edit. hehehe did't see the Xenaflux post and the reference to a text book
printed in England