I think, therefore I am

Loitering on Faraz's Blog, I spotted Descartes' infamous phrase "I think, therefore I am" (Cogito, ergo sum). Rattled off a train of memories of the various places and events where we used this phrase :)

 

Oh, and I remember a joke about it:

 

Descartes is sitting in a bar, having a drink. The bartender asks him if he would like another. "I think not," he says, and vanishes in a puff of logic.

 

:P