For scholars and laymen alike it is not philosophy but active experience in mathematics itself that can alone answer the question: What is mathematics?
Richard CourantWith an absurd oversimplification, the 'invention' of the calculus is sometimes ascribed to two men, Newton and Leibniz. In reality, the calculus is the product of a long evolution that was neither initiated nor terminated by Newton and Leibniz, but in which both played a decisive part.
Richard CourantStarting in the seventeenth century, the general theory of extreme values - maxima and minima - has become one of the systematic integrating principles of science.
Richard Courant