If you use the slip-box for a while, you will inevitably make a sobering discovery: The great new idea you are about to add to the slip-box turns out to be already in there. Even worse, chances are this idea wasn’t even yours, but someone else’s. Having the same thought twice or mistaking another person’s idea with our own is far from unusual. Unfortunately, most people never notice this humbling fact because they have no system that confronts them with already thought thoughts.
