From Descartes's Error To Sartre's Insight... The section of chapter 2 discusses two philosopher's observations. "I think, therefore I am" was the statement Descartes, the 17th century philosopher, claimed was the root of his being. Descartes didn't realize he had found the root of the ego, thought... About 300 years later a philosopher, Jean-Paul Sartre, contemplating Descartes statement proclaimed... "The consciousness that says 'I am' is not the consciousness that thinks". Sartre, didn't know the significance of his statement either. What Sartre meant Eckhart Tolle explains it with brain surgeon like precision , "When you are aware that you are thinking, that awareness is not part of thinking." Many people refer to this as awakening from the dream!