Newton's Principia and the Clockwork Universe

In 1687 Isaac Newton published the Mathematical Principles of Natural Philosophy, usually called the Principia. It set out three laws of motion and a law of universal gravitation showing that the same force that makes an apple fall keeps the Moon in orbit. With one set of mathematical laws, Newton explained Kepler's planetary orbits, the tides and the paths of comets. Many readers concluded that the universe worked like a vast, orderly machine whose laws reason could discover.

Enlightenment writers such as Voltaire and Émilie du Châtelet spread Newton's ideas in France, where they displaced Descartes's theories by the mid-1700s. Some went further than Newton himself, who was deeply religious and believed God actively sustained the universe. Newton's success became the model for the Enlightenment: if nature had discoverable laws, many thinkers asked, why not society, economics and morality too?