René Descartes was a truly amazing person. He invented analytic geometry, giving us the standard notation we use today for avariables, and created the coordinate plane system, allowing us to graphically represent algebraic equations.
He is known for having creating the “rule of signs,” a method for determining the number of positive and negative roots of an equation. He also invented exponential notation and figured out the principal of refraction, creating what today is known as Snell’s Law.
In summary, he gave math teachers a plethora of ways to torture students.
Perhaps even more amazing is that mathematics was only a hobby of Descartes. His primary focus in life was philosophy, employing his “method of doubt” in a passionate search for truth. With his establishment of using logic and reason to define the natural sciences, he is known as “the father of philosophy.”
And as such, the one thing he is best known for is his famous philosophical declaration, “Je pense, donc je suis,” a statement of proof of being.
You probably know it as, “Cogito, ergo sum,” or “I think, therefore I am.”
Whether or not one exists, philosophers and psychologists are still debating who exactly is the “we” who thinks?