5 July 1687 July 4, 2014 Author: Staff Sir Isaac Newton publishes Philosophiæ Naturalis Principia Mathematica. Famous Words of Inspiration..."Happiness does not come from doing easy work but from the afterglow of satisfaction that comes after the achievement of a difficult task that demanded our best." Theodore Isaac Rubin — Click here for more from Theodore Isaac Rubin Related posts: 4 July 1569 5 July 1948 5 July 1948 5 July 1946 29 May 1953 29 May 1953 Categories: History Tags: 1687, 5 July