Δαφνη Ευτυχια Αρθουρος

"Once one has been initiated into the calculus, it is hard to remember what it was like not to know what a derivative is and how to use it, and to realize that people like Fermat once had to cope with finding maxima and minima without knowing about derivatives at all." -- Judith V. Grabiner, "The Changing Concept of Change: The Derivative from Fermat to Weierstrass", April 1982