I've been thinking lately about Descartes' idea that we are simply a res cogitan. I completely disagree (as the ultimate subject of attribution in a rational being is the person, not a nature and certainly not a power). But, while thinking about this, my brain naturally went to a joke I had heard a few years ago.
Descartes walks into a Cafe in Paris to have a coffee. As the waiter pours his coffee for him, he asks, "Sir, would you care for any cream or milk?" to which Descartes replies, "I think not." and disappears.