Philosophiæ Naturalis Principia Mathematica
Many of the discoveries and mathematical formula found within Newton's "Philosophiæ Naturalis Principia Mathematica" can be linked, often very directly, to his occult and alchemical studies. Much of his research into the movement of heavenly bodies was influenced by his belief that there are invisible, occult forces at work in the orbits of celestial bodies. Other natural philosophers, most notably Descartes, tended to object to this notion and insisted instead that action depended on physical contact, proposing that celestial objects were moved about by a great many small particles.