A horse walks into a bar.

The bartender says "You're in here a lot. Are you an alcoholic?"

The horse thinks about it for a minute before saying "I don't think I am."

*POOF* The horse vanishes.

Students of philosophy, by now, are chuckling, as they're familiar with Descartes postulate "I think, therefore I am."

If I'd have told you that at the beginning, however, I would have been putting Descartes before the horse.