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The Enlightenment (1650–1800)

History SparkNotes

The Roots of the Enlightenment

Key People & Terms

The English Enlightenment

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

The Legacy of the Scientific Revolution

During the Scientific Revolution, physics, philosophy, earth science, astronomy, and mathematics all experienced bold new innovation. Even more significant, the methods of scientific exploration were refined. The thinkers of the Scientific Revolution generated the concepts of inductive and deductive reasoning, as well as the general observe-hypothesize-experiment methodology known as the scientific method. Ultimately, these movements yielded the work of Newton, who is considered one of the most influential scientists of all time. His approach to the world encouraged observation and the realization not of causes but of effects. Just as important, Newton showed that scientific thought and methods could be applied to nonscientific topics—a development that paved the way for numerous later thinkers of the Enlightenment.

Exploration and Imperialism

In addition to these scientific milestones, political and cultural change was taking place in Europe as the result of exploration and the extension of overseas empires, especially in the Americas. In addition to the brand-new discovery of America, European explorers also used new transportation technologies to explore already-known locales in Africa and Asia in greater depth than ever before.

As these explorers returned from across the world with stories of peoples and cultures never previously known, Europeans were introduced to drastically different lifestyles and beliefs. Some explorers brought foreign visitors to Europe, which introduced common people—who wouldn’t otherwise be able to travel—to these foreign influences. The Orient especially mystified Europeans: its religions, familial relationships, and scientific discoveries astounded Westerners to such a degree that the emulation of Chinese culture briefly came into fashion. All in all, this worldlier perspective provided Enlightenment-era thinkers with the inspiration and impetus for change.

The Declining Influence of the Church

Yet another major change in the lives of Europeans prior to the Enlightenment was the weakening of adherence to traditional religious authority. The questioning of religion itself can largely be traced to the tensions created by the Protestant Reformation, which split the Catholic Church and opened new territory for theological debate. Additional seeds were planted by Baruch Spinoza (16321677), a Jewish lens grinder and philosopher from Amsterdam who developed a philosophy emphasizing ethical thought as the guide to conduct. Spinoza called into question the tenets of both Judaism and Christianity: he believed in God but denied that the Bible was divinely inspired and rejected the concept of miracles and the religious supernatural. He claimed that ethics determined by rational thought were more important as a guide to conduct than was religion.

As other seventeenth-century thinkers similarly questioned the authority of organized religion, it became much more common in European intellectual circles to put the concepts of religious belief to question. Although the Church’s influence still remained strong, especially among the lower classes, the ideas of Spinoza combined with the new discoveries of the Scientific Revolution threatened the supremacy of Church doctrine considerably. Most devastating was the philosophical approach many scientists were taking, which often led to conclusions that God either did not exist or at least did not play much of a role in daily life.

Moreover, these advances in thought coincided with anti-church and government sentiment that was already growing among European commoners. The Catholic Church at the time was famously corrupt, and it often ruled using intimidation, fear, and false knowledge and was violently intolerant toward dissenters and heretics. Subsequently, when Enlightenment philosophers came along praising liberty and self-empowerment, they found willing ears.

The Thirty Years’ War

Another major change in Europe prior to the Enlightenment was an increased questioning of the justness of absolute monarchy. For centuries, the common citizens of Europe had little or no role in their governments. During the seventeenth and eighteenth centuries, however, developments occurred that caused the authority of European divine right—the idea that monarchs were infallible because their titles were granted by God—to weaken. Perhaps the most immediate catalyst of the Enlightenment in this regard was the Thirty Years’ War, which broke out in 1618 when Bohemian Protestants revolted against their incoming Catholic king. The ensuing battle between Protestants and Catholics spread into Germany, and over the course of the next thirty years, nearly a third of the German population was killed.

The First Enlightenment Thought

The atrocities that the German public endured over those three decades inspired leading European thinkers and writers to decry war as an institution. Czech reformer John Comenius (15921670) questioned the necessity of war, emphasizing the similarity of man by writing that “we are all citizens of one world, we are all of one blood.” Meanwhile, Dutch thinker Hugo Grotius (15831645) wrote that the right of an individual to live and exist peacefully transcends any responsibility to a government’s idea of national duty. Grotius’s desire for humane treatment in wartime was expressed in his On the Law of War and Peace (1625), which proposed such wartime policies as the declaration of war, the honoring of treaties, and humane treatment of war prisoners.

Comenius’s and Grotius’s antiwar sentiments were the first developments of the Enlightenment in the sense that they went against tradition and took a humanistic approach to the atrocities in the world. Grotius was perhaps most significant for defining the God-given duties of man and then showing how war infringed upon them, thus “proving” that war is wrong. Comenius, for his part, went so far as to question the idea of nationalism and the obligation one has to give one’s life for one’s country.

Individualism, Relativism, and Rationalism

Ultimately, from this slew of scientific, cultural, social, and political developments in Europe during the sixteenth and seventeenth centuries emerged three fundamental ideas that encompassed everything the Enlightenment would stand for. First among these was individualism, which emphasized the importance of the individual and his inborn rights. The second, relativism, was the concept that different cultures, beliefs, ideas, and value systems had equal merit. Finally, rationalism was the conviction that with the power of reason, humans could arrive at truth and improve the world.

These three ideas reveal the fundamental concepts that would pervade the Enlightenment—man’s ability to reason, to look past the traditions and conventions that had dominated Europe in the past, and to make decisions for himself. Moreover, these ideas represented the separation and autonomy of man’s intellect from God—a development that opened the door to new discoveries and ideas and threatened the most powerful of Europe’s long-standing institutions.

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