Why?

I am starting the blog because it seems I have recently become obsessed with "The List", and find it fascinating. Ok well that is not entirely true - I have always been a list person, but I really just did one when I really needed to get something done. I made a list for the supermarket, I made a list of things to do for a weekend. I made a list when I am packing a suitcase. However, recently I have made a list that encompasses everything and I even have "sub-lists". I get things done and cross them off the list, but I find myself adding more than I am crossing off.

Why do we keep lists? Why do we add more to the list than we can possibly get done? Why don't we throw the list out when we get done and start a new list?

Are there other obsessive list people out there?