Cartesianism is a philosophical system developed by the French philosopher René Descartes in the 17th century. It emphasizes the use of reason and doubt as a means to achieve certainty. Descartes is famous for his statement, "Cogito, ergo sum," which means "I think, therefore I am." This idea highlights the importance of self-awareness and consciousness in understanding existence. In addition to its philosophical implications, Cartesianism also influenced mathematics and science. Descartes introduced the concept of Cartesian coordinates, which allows for the representation of geometric shapes using algebra. This approach laid the groundwork for modern analytical geometry and has had a lasting impact on various fields, including physics and engineering.