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|Historical Context=When Isaac Newton began his studies at Cambridge University's prestigious Trinity College in 1661, more than a century had passed since Nicolaus Copernicus (1473-1543) had proposed a '''heliocentric cosmology''' in his 1543 ''De revolutionibus orbium coelestium'' (''On the Revolutions of Heavenly Spheres''). It had been fifty years since Galileo Galilei (1564-1642) had published his observations with the telescope in 1610. Galileo had discovered dramatic evidence favoring the Copernican system. His discovery of the phases of the planet Venus indicated that it revolved around the sun and was lit by reflected sunlight. His description of four moons circling Jupiter indicated that Earth, with its own moon, resembled this planet. His studies of sunspots indicated that the sun revolved on its axis, and finally, his discovery of surface features on the moon indicated that the moon was another world, as expected under the Copernican system, but not by Aristotelianism. Around the same time, Johannes Kepler had published his laws of planetary motion, indicating that the planets revolved around the sun on elliptical paths, replacing the circular motion and complex epicycles of Copernicus and Ptolemy. [[CiteRef::Westfall (1980)|p. 1-7]] According to Westfall, "by 1661 the debate on the heliocentric universe had been settled; those who mattered had surrendered to the irresistible elegance of Kepler's unencumbered ellipses, supported by the striking testimony of the telescope, whatever the ambiguities might be. For Newton, the heliocentric universe was never a matter in question." [[CiteRef::Westfall (1980)|p. 6]]
Newton’s education at Cambridge was nonetheless classical, focusing on Aristotelian rhetoric, logic, ethics, and physics. The curriculum had changed little in decades, despite the incompatibility of Aristotelian natural philosophy with Copernican heliocentrism [[CiteRef::Westfall (1980)|p. 81-90]][[CiteRef::Smith (2009)]] Like many of the more ambitious students, Newton is known to have distanced himself from classical metaphysics and instead studied the works of '''[[René Descartes]]''' (1596-1650) on his own. By 1664, Newton is known to have read the 1656 Latin edition of Descartes' ''Opera philosophica'', a compilation which included ''Meditations on First Philosophy'', ''Discourse on Method'', ''Dioptrics'', and ''The Principles of Philosophy'' [[CiteRef::Smith (2009)]] Descartes had died just over a decade prior, and his major works had first been published within the preceding thirty years. His works were gaining in popularity and by about 1680 would become the [[Theory Acceptance|accepted ]] centerpiece of the Cambridge curriculum [[CiteRef::Barseghyan (2015)|p. 190]].
Both Newton’s physics and philosophy were heavily influenced by Descartes’ ideas. Descartes' mechanical natural philosophy was derived from ancient Greek atomism, which had been reintroduced into Europe in the fifteenth century. Descartes was the most prominent member of a community of corpuscularist thinkers. Although corpuscularists rejected the idea of ultimate atoms in a void space, they nonetheless maintained that visible objects were made of unobservably tiny particles, whose relations and arrangement were responsible for the properties of visible bodies. This means of explaining the properties of visible objects replaced Aristotle's forms. Descartes' theories explained gravity as due to a swirling vortex of particles around the Earth. Because he envisioned a similar vortex to surround the sun, his theories were consistent with Copernican heliocentrism [[CiteRef::Garber (1992)]]. Although he disagreed with many of the theories about the natural world adopted in the Cartesian mosaic, it was clear that Newton viewed the Cartesian mosaic as a step forward from the preceding Aristotelian-scholastic one.[[CiteRef::Janiak (2016)|p. 55]] When structuring his view of the natural world, Descartes based his model on a Copernican view of the universe, as opposed to the classical geocentric understanding. The previous Aristotelian theory of motion had been contingent on geocentrism,[[CiteRef::Disalle (2004)|p. 37]] as when the Earth is at the centre of the universe, all motion could be explained causally according to whether the moving object in question existed in the terrestrial or celestial realm, which in that mosaic were thought to be fundamentally different.[[CiteRef::Bodnar (2016)]]
Once Descartes had adopted Copernican heliocentrism, the causal theory of motion as understood by Aristotelian-scholastic natural philosophers had to be replaced along with its cosmological model.[[CiteRef::Disalle (2004)|p. 48]] Cartesian mechanics was developed around a radical comprehension that the source of motion was the same for all bodies in the universe. This idea acted as a pillar upon which a new, mechanical philosophy was constructed. According to this philosophy, the source of all motion of material objects is direct, physical contact with other material objects. The mechanical philosophy was adopted by Gottfried Leibniz, Christiaan Huygens, and many other prominent scientists who worked alongside Newton, indicating that much of later 17th century science was deeply rooted in Cartesian philosophy.[[CiteRef::Disalle (2004)]]
