Rene Descartes (1596–1650) was a seminal figure in the scientific revolution of the 17th century. This was a revolution in the full sense of that word: an old worldview was overturned and rejected in favor of a new, very different worldview. This new worldview was based on hypothesis and experiment, on reducing scientific phenomena to a very few, simple mathematical formulae. The old worldview was Aristotelian scholasticism: a worldview closely tied to the Catholic Church, which had been the exclusive seat of learning in the West since the fall of the Roman Empire. The Aristotelian worldview was based on reason and logical deduction. Truth was something that could be known with certainty and deduced from other self-evident truths.
The old worldview of Aristotelian scholasticism was not going to go down without a fight. Many of the advocates of the new science—Descartes and Galileo being two notable cases—still used much of the language and terminology of the Catholic academics. When they tried to work against this system, the church would often come down hard: in 1633, the Inquisition condemned Galileo's theories—in particular his theory that the earth revolves around the sun—and placed him under house arrest. This was the same year that Descartes completed The World, a lengthy discussion of his scientific views that were not altogether out of sympathy with Galileo's. Descartes was preparing it for publication, when, upon discovering that Galileo had been condemned, Descartes hastily suppressed his manuscript.
Though he dedicated his entire adult life to research in philosophy, mathematics, and science, Descartes did not publish anything until he was forty years old, largely due to his fears of censure. His first publication, in 1636, was the Discourse on the Method along with three scientific essays, one on optics, one on meteorology, and one on geometry.
The Discourse itself is meant to serve as a preface for these three essays, but it has since far surpassed them in reputation. While the essays are now rarely read, the Discourse itself has endured. The Discourse is intended to introduce the scientific method that Descartes has invented and to explain how his views came about and why he has been so hesitant to publish them, while the essays are meant to serve as evidence of the fruits of his labor. The Discourse does not just give us insight into Descartes's philosophy and his method; it also gives us insight into the intellectual climate of his day.