Our conception of the past is littered with expressions that are often poorly defined or understood: ancient, barbarian, empire, liberal, progress, capitalism. The distinguished historian J. C. D. Clark wishes to draw our attention to the equivocal character of another widely used term: Enlightenment.

To be precise, the more problematic formulation is “the Enlightenment,” not “enlightenment” per se. In a phrase that appears multiple times in his latest work, The Enlightenment: An Idea and Its History, and that might be considered a simplified statement of its thesis, Clark contends that across Europe in the seventeenth and eighteenth centuries, “enlightenment was everywhere, but the Enlightenment was nowhere.” He sets out to demonstrate that the Enlightenment—a mainstay of intellectual, social, and political history—is in fact a figment of our imagination. It never happened.

Well, not quite. Clark insists that his book does not claim “the Enlightenment never happened,” but here he is being coy. Clark acknowledges that enlightenment, with a lowercase e, certainly did happen. Conventionally understood “Enlightenment” figures, such as Voltaire, David Hume, and Immanuel Kant, did attempt to improve the human condition by illuminating darkened minds, by liberating mankind from the shackles applied by kings and priests. There were individuals and movements that sought political, racial, and sexual equality. Yet, Clark contends, “the rhetoric which came to celebrate a unitary Enlightenment in western Europe and North America was overstated,” the “values and practices within and between those societies over time displayed some commonalities, but more differences,” the “emergence of the concept and the idea of a movement which that concept appropriately labelled was much later than was even recently assumed,” and “in the century in which the Enlightenment is usually located there was not one interesting and important thing happening, but many.”

In brief, Clark wishes to complicate drastically the conventional picture of the Enlightenment, with a capital E. The Enlightenment that did not happen is the one that is an actor in history, a discrete and intelligible movement encompassing many people across many national boundaries. This Enlightenment, Clark avers, is a reification—he uses the word frequently—a term which seemingly bestows concrete form on what is in fact only an ethereal concept.

Clark certainly marshals his evidence adroitly. Ranging across four centuries (1600–2000) and as many national contexts (England, Scotland, France, and Germany—with a few others treated briefly as necessary), he presents close readings of key texts as well as correspondence produced by major figures commonly associated with the book’s theme. The erudite 500-page tome is not for the casual reader—many French passages are presented sans translation, for example. All along the way, Clark stresses disagreement, discord, and disorganization. In his telling, thinkers such as Locke, Diderot, and Rousseau had no common political, social, or philosophical program; instead, each had his own idiosyncratic set of concerns, arising from personal experience and responding to a particular context.

In the process, Clark focuses on personal interactions and relationships (or lack thereof), revealing interesting affinities and conflicts. The friendship between the celebrated English authors Mary Wollstonecraft and Samuel Johnson, for example, belies conventional Enlightenment narratives that would predict “a proto-feminist and revolutionary being savaged by the reactionary misogynist of literary legend.” Instead, Clark notes, the two had commonalities that might explain a natural attraction: “Both authors made their way in life despite social handicaps,” he writes. “Both were Anglicans, but went beyond simple denominational boundaries. Both approved, and disapproved, of the establishment into which they had keen insights. For both, virtue and reason were allies, and both qualities fought together on a field of battle laid out by Providence.”

In the encounter between the two, Clark observes, “there is no evidence of a confrontation between Enlightenment and Counter-Enlightenment.” In contrast, Wollstonecraft expressed overt hostility toward Rousseau, her purported Enlightenment ally. The English thinker objected especially to her French counterpart’s treatment of women—both personally and intellectually—accusing Rousseau of harboring the belief that “woman is expressly formed to please the man,” a view she characterized as “the philosophy of lasciviousness.”

This is just one example among a multitude of such cases that Clark adduces by way of contesting customary lines of demarcation between the “good” side of Enlightenment and the “bad” side of reaction. If there were so much tension and so few common convictions among so-called Enlightenment figures, does it make sense to continue to think of them as part of a coherent, discernible movement?

In addition to exploring the writings of “Enlightenment” luminaries, Clark undertakes a linguistic analysis of the word itself. He finds no substantial evidence that there was a meaningful intellectual or social movement that saw itself as ushering in an enlightened age on the heels of a shadowed past. The first glimmering of explicit discussion of the Enlightenment—the late eighteenth-century discourse among German scholars concerning Aufkläring—did not reflect a wider movement. “This German debate on the meaning of the term,” he observes, was “unique: in the 1780s and earlier there was no corresponding French debate on les lumières, no Spanish debate on las luces, no English debate on the Enlightenment.”

Especially impressive is Clark’s fine-grained comparison of translations of original works by Enlightenment writers, from those authors’ original languages into other European tongues. Clark finds that many seeming indications of “Enlightenment” consciousness were in fact impositions on the original text applied by later translators who assumed (or were attempting to create) the Enlightenment context in which the authors originally wrote. For example, though the earliest English translations of D’Alembert’s Preliminary Discourse “made no use of the term ‘enlightenment,’” a 1963 American rendering employed it in several passages.

This evidence is important, because Clark’s argument is that, while “the Enlightenment” did not really happen in the seventeenth century, it did happen in the nineteenth and twentieth centuries—as a historiographical event. “The Enlightenment,” he asserts, “was not a precocious and international reality but a recent term of historiographical art.” The term was “hardly used in the English-speaking world before the mid twentieth century but then and later projected back onto the eighteenth for presentist purposes.” That is, the so-called Enlightenment that supposedly occurred in France and Scotland and elsewhere played a critical role in contemporary political and intellectual debates, and in this way “the Enlightenment,” as a reification, did indeed have an impact on history.

Clark’s case is largely persuasive. He is certainly correct that “the Enlightenment” is a problematic historical designation. There was much dissension among Enlightenment figures, and positions and attitudes varied across and within national contexts. As Clark notes, this complexity has been widely acknowledged among European intellectual historians for some time.

The lesson has wider application. Historians (and others) do well to avoid—or at least use with extreme caution—terms that reify concepts and thereby hold the potential to obscure rather than illuminate what actually happened in the past. Contemporary discussions of “liberalism” and “nationalism” are rife with violations of this rule.

Yet Clark seems to want to go further, to discard “the Enlightenment” altogether as a meaningful historical term—or, at least, modify its meaning so radically that it applies only to the historiography of the Enlightenment. But there may be other, less disruptive ways of dealing with the problems identified.

David Hume, Clark notes, “did not see himself as part of a movement.” Clark suggests that “a thinker of Hume’s extraordinary abilities might well have inspired a school of followers explicitly acknowledging their debt to him; but this did not happen.” So there was no explicit movement known as the Enlightenment. But this doesn’t necessarily mean that Hume wasn’t part of an implicit movement—a movement filled with tension, even contradiction; a movement whose figures often quarreled and who did not even see themselves engaged in a common project. Might such a ragtag group nonetheless, from the vantage point of history, be roped together as an identifiable and significant phenomenon? This is admittedly, in part, a semantic question: What constitutes a historically meaningful “movement”? But it is also a question regarding the latitude historians should enjoy in creating coherent narratives out of a seemingly chaotic and disorderly past.

Acknowledging that Clark is right about the ambiguous and problematic nature of the term Enlightenment, the same might be said of a vast number of common historical categories and conventions. The Middle Ages and its cognate medieval are similarly problematic, laden with historically contingent judgments imposed by later historians with axes to grind. But they are also so deeply embedded in the narrative of European history that it is hard to imagine eradicating them. Unless and until a better way of periodizing the past two thousand years comes along, we are stuck with them. To be sure, they should be employed with full cognizance of their inadequacies, but it could be that the benefits of avoiding them altogether do not justify the costs.

Clark is not unaware of the problem. He is skeptical about the use of concepts in historical method, having justly shown how much mischief they can cause. But his approach raises questions that he himself poses: “Are concepts essential to intellectual enquiry? If so, are they of timeless validity and not to be questioned? Can historians historicize one key concept without calling in question all concepts?” The language of the Enlightenment will likely not disappear from our discussions of the past, but those who continue to use it should, thanks to J. C. D. Clark’s learned and forceful critique, do so with more profound awareness of its drawbacks.