The fact that one exists is one of the most basic of all concepts. If there is anything that can be taken for granted, that is it. Just the fact that you're wondering means that you're here to wonder, right? Questioning one's own existence has got to be the silliest thing since helmets on skydivers. So why am I questioning it, then? I know it's silly, but I'm not sure of my own existence, or why that uncertainty bothers me. Hell, I'm not even sure if I should bother thinking along this vein. ... but I know damn well that I will, so I guess I might as well do it right, eh?