Many historians believe that a Scientific Revolution occurred roughly between the years1550 and 1700. It is marked by a period of dramatic and historically rapid changes in the ways in which scholars thought about the physical world and studied it and laid the foundation of Modern Science. Most sources list the "Scientific Revolution" as the period between Copernicus publication of'De Revolutionibus Orbium Coelestium' (On the Revolutions of Celestial Bodies) and Newton's publication of 'Philosophia Naturalis Principia Mathematica'.