Newton codified the laws of motion and gravity, their primitive forms being enunciated in 1665-66. Using Kepler's laws, he discovered the inverse square law of gravity and went on to show that gravity is the same force which holds the planets in their orbits, as well as that which causes apples to fall to the ground. Newton was a brilliant experimentalist who invented the Newtonian, reflecting telescope which eliminated the aberrations of refracting telescopes such as those built by Galileo. Newton's researches culminated in the publication of his revolutionary Principia Mathematica of 1687. He devoted as much effort to chemical (or alchemical) analyses and to the interpretation of ancient texts and the scriptures. He was also the inventor of differential and integral calculus.