Diderot’s Encyclopedia: The Spirit of Enlightenment

FROM THE LECTURE SERIES: Turning Points in Modern History

By Vejas Gabriel Liulevicius, Ph.D., University of Tennessee, Knoxville

Diderot’s encyclopedia was born out of the spirit of Enlightenment. It was a treasury of knowledge that was revolutionary, encapsulating the ideas of the time. Diderot gave voice to that spirit—“All things must be examined, debated, investigated without exception, and without regard for anyone’s feelings.”

Reading of Voltaire's tragedy The Orphan of China in the salon of Marie Thérèse Rodet Geoffrin.
Reading of Voltaire’s tragedy The Orphan of China in the salon of Marie Thérèse Rodet Geoffrin. Thinkers of the Enlightenment period expounded their ideas in such gatherings at coffeehouses and salons. (Image: Anicet Charles Gabriel Lemonnier/CC BY 3.0/Public domain)

Diderot’s encyclopedia epitomized the Enlightenment and its ideals. Let us first understand what the Enlightenment movement meant.

The Promises of Enlightenment

In the 18th century, a new set of exciting ideas was sweeping the world. These ideas were given the name—Enlightenment. The very name, Enlightenment, proclaimed that this was the dawn of a new age away from the darkness of the past. Its objective was to break with the past in order to usher possibilities for progress. It aspired to reject old habits and traditions of the past and build a new foundation of life on the basis of reason.

The catchphrase of the Enlightenment movement was “Dare to know”. The movement implored human beings to dare to use their reason and rational faculties. It was an intellectual, social, and political movement that aimed to drag the scientific method from the scholarly treatises to practical spheres of life.

Enlightenment thinkers liked to call themselves philosophes—lovers of knowledge. They valued reason, science, and utility. Their values were opposed to traditional revealed religion, which the philosophes considered to be organized superstition and fanaticism. As rational beings, their goal was to understand the scientific laws that governed the world and use them to improve and perfect human existence.

Enlightenment was the first of the modern secular ideologies. The movement was international, but it was strongest in France.

This is a transcript from the video series Turning Points in Modern History. Watch it now on The Great Courses Plus.

Diderot’s Encyclopedia: The Enlightenment Encyclopedia

These philosophes of Enlightenment in France banded together under the stewardship of Denis Diderot and went on to produce a daring printed work, Encyclopédie, subtitled A Systematic Dictionary of the Sciences, Arts, and Crafts, by a Company of Men of Letters. This diverse group of men (and perhaps a few women as well, hiding under pseudonyms) included priests, aristocrats, middle-class and lower-middle-class writers. Contributors to the Encyclopédie also included celebrities, like Voltaire and Rousseau, and other less-known scholars like Louis de Jaucourt.

Portrait of Denis Diderot, 1767.
Denis Diderot was a luminary of the Enlightenment era. (Image: Louis-Michel van Loo/Public domain)

Enlightenment ideas permeated Diderot’s encyclopedia. The very word ‘encyclopedia’ conveyed a particular vision of the world—it meant that the world was knowable. The word encyclopédie has two Greek roots—kyklos which means circle, and paideia which means knowledge. Therefore, an encyclopedia was a linking of knowledge, an establishing of connections and interrelations. The editors of the encyclopedia believed that all knowledge was interconnected. The Enlightenment reinforced the encyclopedic urge to catalog, to classify, and to order the existing wealth of knowledge by means of reason.

Learn more about Gutenberg’s Print Revolution.

A Call to Modernity and Reason

It was customary then, for even innovative thinkers, to turn to the past and to the classics in order to make a claim for authority. For example, the Renaissance was known as a rebirth or recovery of classical knowledge. In contrast, the editors of the Encyclopédie laid claim to the modernity of their project and its fundamental discontinuity with the past. In his introduction, Diderot wrote that only in his era could such a work have been produced and that it took “more intellectual daring” than earlier ages had possessed.

The title page of the Diderot's Encyclopédie.
The title page of the Diderot’s Encyclopédie. The encyclopedia conveyed the messages of the Enlightenment. (Image: Several contributors, Final edit by Jaybear/Public domain)

The entry on Philosophe in the Encyclopédie says: “Reason is to the philosopher what grace is to the Christian. Grace causes the Christian to act, reason the philosopher.” Further, the text announced, “While others walk in darkness, steered by their passions, the philosophe has reason to light his way.”

The Encyclopédie aimed to reach and be of benefit to all humanity. This was in stark contrast with prior ages when a class of clerics or a guild of artisans held the secrets of their craft and trade. The great promise held by both the Enlightenment and the project of the Encyclopédie was progress. Where earlier ages constantly looked backward for guidance, now progress in the future was invoked as the guiding authority.

Learn more about the French Revolution.

The Enormous Impact of the Encyclopédie

The Encyclopédie had 72,000 entries and more than 2,500 plates of illustrations. This was the largest reference work and publishing project of its time. It was read by individuals and families, by reading clubs and societies, and its message of Enlightenment went near and far. The project was hugely popular in and outside France. The Encyclopédie was reprinted in multiple editions, reaching an estimated 25,000 sets. In addition, scores of pirated and plagiarized editions also followed, all of which spread the message even further.

Encyclopédie was not the first encyclopedia or comprehensive reference guide, but nonetheless it was a landmark achievement. It inspired future thinkers with its lofty goals of democratization of knowledge and improving the state of humanity with reason and science. It was an embodiment of the Enlightenment movement—the movement to replace tradition and faith with reason, science, and useful knowledge. The avowed aim of the Encyclopédie was nothing less than “to change the way people think”, the most ambitious change of all.

The impact of the Encyclopédie was enormous. When Diderot died in 1784, his last words were: “The first step toward philosophy is incredulity.” Meaning that the first step was not to believe. This was a radical message—testing everything was necessary. In the decades to come, when empires and kingdoms were tested, in part by the ideas enshrined in the Encyclopédie, the result would be revolutions.

Common Questions About Diderot’s Encyclopedia

Q: What did Diderot’s encyclopedia do?

Diderot’s encyclopedia was a project for linking knowledge and establishing connections and interrelations. It was the largest reference work and publishing project of its time.

Q: What was the impact of Diderot’s encyclopedia?

Diderot’s encyclopedia lit the flame of Enlightenment among its readers. It inspired them to question authority and dare to learn more.

Q: What were Diderot’s beliefs?

Diderot believed in materialism. He believed that all things must be examined, debated, and investigated without exception and without regard for anyone’s feelings.

Q. What was the Enlightenment philosophy?

The Enlightenment philosophy aspired to reject old habits and traditions of the past and build a new foundation of life on the basis of reason.

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