5 July 1687 Posted on July 4, 2015 by Staff Isaac Newton publishes PhilosophiƦ Naturalis Principia Mathematica. Famous Words of Inspiration..."Most writers regard truth as their most valuable possession, and therefore are most economical in its use." Mark Twain — Click here for more from Mark Twain Related posts: 5 July 1687 17 October 1979 4 July 1569 5 July 1948 5 July 1948 5 July 1946