Sir Isaac Newton begins his so called annus mirabilis (miraculous year) during which he developed his most famous theories including that of gravity, the nature of light and calculus.


Further info :

Newton - Laws

Sir Isaac Newton: The Universal Law of Gravitation
http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html


Isaac Newton:
http://galileoandeinstein.physics.virginia.edu/lectures/newton.html