I am the center of gravity, hold a capital situation in Vienna, and as I am foremost in every victory, am allowed by all to be invaluable. Though I am invisible, I am clearly seen in the midst of a river. I could name three who are in love with me an... Read more of I am the center of gravity, at Free Jokes.ca
You'll need a pencil and a flat surface.(preferably a table you can sit at)
Place pencil on table, roll it towards you, before it rolls off the side, put your hands over the pencil and push it without touching it or imagine it rolling the opposite direction.
You might have to develop your own way to do this but it's very simple and even a mortal could do this. My mortal friends are actually very good at it.