The quote "I think, therefore I am" is attributed to the French philosopher René Descartes. This statement, originally in Latin as "Cogito, ergo sum," encapsulates Descartes' philosophical approach to knowledge and existence. In his work "Meditations on First Philosophy," Descartes sought to establish a foundation for scientific knowledge based on reason and doubt. This famous declaration signifies that the act of thinking is proof of one's existence and consciousness, marking a significant moment in the history of philosophy and the development of modern thought.