July 5, 1687

On this date, the Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) by Isaac Newton was published.  This three-volume work contains the statement of Newton’s laws of motion forming the foundation of classical mechanics, as well as his law of universal gravitation and a derivation of Kepler’s laws for the motion of the planets (which were first obtained empirically).   The Principia is widely regarded as one of the most important scientific works ever written.  It is in a supplement to the Principia, entitled General Scholium, that Newton expressed his famous “Hypotheses non fingo” (“I feign no hypotheses” or “I make no guesses”).