Context
René Descartes (1596 - 1650) was born near Tours, in France, and was educated for nine years at a Jesuit college. After graduating with a law degree from Poitiers at the age of twenty-two, he traveled about Europe, developing a passion for mathematics and philosophy. He spent most of his life after 1628 in Holland, and published in philosophy, physics, mathematics, and other sciences. In mathematics, he invented analytic geometry and the coordinate system that bears his name ("Cartesian"). He also prepared some significant works in physics, which he withdrew from publication upon discovering that his contemporary, Galileo, had been condemned by the Inquisition for teaching that the earth rotates around the sun, a theory that Descartes also supported. His great achievement, however, is the Meditations, published in 1641, and generally considered the starting point for modern Western philosophy. It was widely read and discussed even in Descartes' day. In 1649, Descartes accepted an appointment as tutor for Queen Christina of Sweden. She demanded that her lessons take place at five o'clock in the morning, and the strain of rising early coupled with the unbearable cold of Sweden gave Descartes pneumonia and killed him within a year.
Descartes was writing at a time when a new physics was being developed by Galileo and others. This new physics could be understood as a mathematization of nature. Galileo and others began understanding the processes of movement and change in the universe as being formalized in a small number of mathematical relationships. This led to an understanding of the universe as being governed by a very few, simple, abstract, mathematical principles. The metaphysics developed in the Meditations is meant to serve as an underpinning for the new physics being developed at the time. Descartes saw his reason-based and mathematically-inclined metaphysics as providing all the foundations necessary to develop his own physical principles.
Descartes was also writing at a time when Catholic philosophy inherited from Aristotle had a tremendous influence. Descartes himself was raised in the Jesuit tradition, and the Meditations in many ways resemble St. Ignatius of Loyola's Spiritual Exercises. Both are framed in a meditational form meant to span six days' meditation. Descartes also imitates Loyola's three stages of purgation (skeptical doubt), illumination (proof of the existence of the self, of God), and union (linking this knowledge to the material world). In imitating Loyola's style, and opening the Meditations with a very Aristotelian outlook, Descartes hoped to seduce the conservative thinkers of his day into following his line of reasoning. After having witnessed Galileo's fate, he had every reason to be cautious. This method also makes Descartes far more accessible to the largely Jesuit audience that he is addressing.
