The Enlightenment (1650–1800)

by: History SparkNotes

The Roots of the Enlightenment


1605Kepler discovers first law of planetary motion
1609Galileo develops his first telescope
1618Thirty Years’ War begins
1625Grotius publishes On the Law of War and Peace
1633Pope prosecutes Galileo for promoting sun-centered theory of the solar system
1648Thirty Years’ War ends
1687Newton publishes Philosophiae Naturalis Principia Mathematica

Key People

Galileo Galilei - Italian astronomer who supported the sun-centered Copernican model of the solar system, angering the Catholic Church
Johannes Kepler - German astronomer who discovered laws of planetary motion
Francis Bacon - English scholar who developed inductive method of reasoning
René Descartes - French mathematician and philosopher who revolutionized algebra and geometry, developed deductive method
Isaac Newton - English mathematician and physicist who formulated fundamental laws of gravity and motion
Baruch Spinoza - Dutch-Jewish thinker who questioned many tenets of Judaism and Christianity
John Comenius - Czech reformer who questioned necessity for war
Hugo Grotius - Dutch scholar who explored concepts in international relations and outlined laws of “fair” warfare

The Scientific Revolution

The Enlightenment was the product of a vast set of cultural and intellectual changes in Europe during the 1500s and 1600s—changes that in turn produced the social values that permitted the Enlightenment to sweep through Europe in the late 1600s and 1700s. One of the most important of these changes was the Scientific Revolution of the 1500s and 1600s. During the Scientific Revolution, European thinkers tore down the flawed set of “scientific” beliefs established by the ancients and maintained by the Church. To replace this flawed knowledge, scientists sought to discover and convey the true laws governing the phenomena they observed in nature.

Although it would take centuries to develop, the Scientific Revolution began near the end of the Middle Ages, when farmers began to notice, study, and record those environmental conditions that yielded the best harvests. In time, curiosity about the world spread, which led to further innovation. Even the Church initially encouraged such investigations, out of the belief that studying the world was a form of piety and constituted an admiration of God’s work.

Galileo and Kepler

The Church’s benevolent stance toward science changed abruptly when astronomers such as Galileo Galilei (15641642) and Johannes Kepler (15711630) started questioning the ancient teachings of Aristotle and other accepted “truths.” Galileo’s work in the fields of physics and inertia was groundbreaking, while Kepler’s laws of planetary motion revealed, among other things, that the planets moved in elliptical orbits. Galileo especially encountered significant resistance from the Church for his support of the theories of Polish astronomer Nicolaus Copernicus (14731543), who had stated that the sun, not the earth, was the center of the solar system—not vice versa, as Church teaching had always maintained.

Bacon and Descartes

Though up against considerable Church opposition, science moved into the spotlight in the late 1500s and early 1600s. Galileo had long said that observation was a necessary element of the scientific method—a point that Francis Bacon (15611626) solidified with his inductive method. Sometimes known as the Baconian method, inductive science stresses observation and reasoning as the means for coming to general conclusions.

A later contemporary, René Descartes (15961650), picked up where Bacon left off. Descartes’ talents ran the gamut from mathematics to philosophy and ultimately the combination of those schools. His work in combining algebra and geometry revolutionized both of those fields, and it was Descartes who came to the philosophical conclusion “I think, therefore I am”—asserting that, if nothing else, he was at least a thinking being. Descartes’ deductive approach to philosophy, using math and logic, stressed a “clear and distinct foundation for thought” that still remains a standard for problem solving.


As it turned out, all of these developments of the Scientific Revolution were really just a primer for Englishman Isaac Newton (16421727), who swept in, built upon the work of his predecessors, and changed the face of science and mathematics. Newton began his career with mathematics work that would eventually evolve into the entire field of calculus. From there, he conducted experiments in physics and math that revealed a number of natural laws that had previously been credited to divine forces. Newton’s seminal work, the Philosophiae Naturalis Principia Mathematica (1687), discussed the existence of a uniform force of gravity and established three laws of motion. Later in his career, Newton would release Optics, which detailed his groundbreaking work in that field as well.