Cogito, ergo sum relying on clarity, distinctiveness, and self-evidence. Baruch Spinoza in ""Principia philosophiae cartesianae"" at its "Prolegomenon" identified "cogito ergo sum" the ""ego sum cogitans"" (I am a thinking being) as the thinking substance with his ontological interpretation. It can also be considered that "Cogito ergo sum" is needed before any living being can go further in life". Although the idea expressed in "cogito, ergo sum" is widely attributed to Descartes, he was not the first to mention it. Plato spoke about the "knowledge of knowledge" (Greek νόησις νοήσεως "nóesis noéseos") and Aristotle explains the idea in full length: But if life
Cogito, ergo sum exists, then I exist"). In "Descartes, The Project of Pure Enquiry", Bernard Williams provides a history and full evaluation of this issue. Apparently, the first scholar who raised the "I" problem was Pierre Gassendi. He "points out that recognition that one has a set of thoughts does not imply that one is a particular thinker or another. Were we to move from the observation that there is thinking occurring to the attribution of this thinking to a particular agent, we would simply assume what we set out to prove, namely, that there exists a particular person endowed with the capacity