Descartes realized that the fact that he was always thinking was beyond doubt, and so he equated thinking with Being, that is to say, identity-"I am"-with thinking.
Instead of the ultimate truth, he had found the root of the ego, but he didn't know that.
It took almost three hundred years before another famous philosopher saw something in that statement that Descartes, as well as everybody else, had overlooked.
The famous philosopher's name was … !