Isaac Newton’s theory of gravity was published as PhilosophiĆ¦ Naturalis Principia Mathematica in 1687.

Translated, it means “Mathematical Principles of Natural Philosophy”.

Interestingly, Newton wrote it at the persistent urging of well-known astronomer Edmund Halley, a colleague and good friend.

When Newton finished it, Halley had the piece published with his own money.

The Principia described Newton’s laws of motion, Newton’s law of universal gravitation, and a derivation of Kepler’s laws of planetary motion.

The three books are often regarded as one of the most important works in the history of science.