The phrase "I think, therefore I am" is attributed to the French philosopher René Descartes. In Latin, the phrase is "Cogito, ergo sum" and serves as a fundamental element in Cartesian philosophy and epistemology. Descartes used this statement as a foundational element to establish certainty in existence and knowledge. By doubting everything else, he reasoned that the very act of thinking proves one’s existence. This idea has had a profound impact on philosophy, shaping discussions around consciousness and the nature of reality.