Two facts that will probably blow your mind.

1. Think of any individual who has ever lived. Thomas Jefferson, your grandfather, your brother, or the first human being who ever walked the earth. The chances are overwhelming that if you pour yourself a couple of glasses of water, you will soon be consuming a molecule that once passed through the bladder of that individual. Statistical probability doesn't lie, and there are several orders of magnitude more molecules in a glass of water than there are glasses of water in the world.

2. Think of a particularly vivid memory from your childhood. You were there (or you wouldn't remember it), right? Well, actually, you weren't. There isn't a single atom in your body that was in existence when that event occurred. Whatever YOU are, it must be something other than the stuff that makes YOU up ... right?