The British-born historian is not the first writer to knock Enlightenment thinkers off their pedestals. The period's "dark side" has been a recurring theme for more than a century now. Critics (among them Friedrich Nietzsche, the Romantic poets, and Michel Foucault) have charged the Enlightenment as an accomplice to a range of crimes that include not only racism, sexism, and "phallologocentrism," but also bureaucracy, technocracy, ecological devastation, Western imperialism -- even fascism. Indeed, in the eyes of some postmodernists, the "totalizing" tendency of Enlightenment thought -- the aspiration to subsume all of reality in its province -- leads inexorably to totalitarianism.

Despite the long tradition of such critiques, scholars are calling Mr. Sutcliffe's work groundbreaking. It is "not only new but startling" says Sander L. Gilman, director of the humanities laboratory and of Jewish studies at the University of Illinois at Chicago and the author, most recently, of Jewish Frontiers: Essays on Bodies, Histories, and Identities (Palgrave Macmillan). Mr. Sutcliffe is not merely pointing out another way in which the architects of liberal modernity fell short. Rather, he is arguing that the Enlightenment is unintelligible outside the context of its preoccupation with Judaism.

High Anxiety

During the early years of the Enlightenment -- in the mid-1600s -- there was an intense fascination with Jewish themes and texts. The Reformation ushered in a renewed emphasis on the Old Testament, a turning to Christianity's Jewish roots. Scholars in the new discipline of Christian Hebraism mastered Hebrew and pored over ancient Jewish texts like the Kabbalah, "scouring" them, Mr. Sutcliffe writes, "for further proofs of the truth of Christianity" and drawing inspiration from the study of Jewish history.

But much of this new focus on Judaism was laced with animosity toward its subject. In what Mr. Sutcliffe describes as a "barbed embrace," early Enlightenment thinkers simultaneously idealized and repudiated Judaism, an attraction-repulsion that surfaced repeatedly. Indeed, Mr. Sutcliffe writes, philo-Semitism and Judeophobia were "frequently intertwined in the same text and even in the same sentence." Paradoxically, however, as Enlightenment thought became increasingly hostile to religion, it focused on Judaism as the source of Christendom. To attack Christianity at its roots, thinkers such as John Toland and Voltaire turned their critical ire on its Jewish foundations.

For the champions of the new Empire of Reason, Judaism came to represent everything they were against.

To them, Judaism embodied tribalism, scripturalism, legalism, and irrational adherence to tradition. Where the Enlightenment upheld reason, Judaism wallowed in myth. The Enlightenment stood for the universal, Judaism for the particular. Enlightenment meant cosmopolitanism, Judaism insularity. The Enlightenment promised progress, Judaism threatened atavism. In short, the Enlightenment came to define itself, Mr. Sutcliffe argues, as the antithesis of all things Jewish.

It was against the backdrop of this self-image, he argues, that the Enlightenment faced a vexing challenge to its own logic. At the deep heart's core of Enlightenment values was the principle of tolerance. Jews, for Enlightenment thinkers, represented the quintessence of intolerance: intellectually closed off and culturally sealed in.

Can an intolerant group of people be tolerated? If Judaism, as Mr. Sutcliffe frames it, was understood as "intrinsically inimical to any notion of individual intellectual freedom, then how can it be encompassed within the bounds of a toleration that is based on the absolute paramountcy of this ethical value?"

That question, he writes, became a test case for the very sustainability of Enlightenment ideals.

'Gordian Knot'

Mr. Sutcliffe's focus on the Enlightenment's twin fascinations with Judaic themes and the irrational, says Mr. Gilman, "illuminates connections between aspects of European intellectual life" that no other scholar has uncovered. Mr. Sutcliffe, he says, has "cut a scholarly Gordian knot" by demonstrating that some of the Enlightenment's most vital debates involved "dealing with the Jews, Jewish thought, Jewish practices, and Jewish texts."

Mr. Sutcliffe "has contributed to a new understanding of the Enlightenment," says Steven Nadler, a professor of philosophy at the University of Wisconsin at Madison and the author of Spinoza: A Life (Cambridge, 1999), in an e-mail message. In demonstrating the importance of "the Jewish question" for the Enlightenment as a whole, and "especially the limits of its liberalism and toleration," says Mr. Nadler, Mr. Sutcliffe, who himself has Jewish roots, "succeeds in showing that a true understanding of the Enlightenment must take Judaism into account" and will thus change the way scholars approach the subject.At the center of Mr. Sutcliffe's narrative is Baruch Spinoza (1632-77), the Dutch-Jewish rationalist who, because he was not a Christian to begin with, occupied a unique position in the religious-intellectual landscape of the early Enlightenment. Regarded as a heretic by Amsterdam's rabbis for his confounding formulation that God and nature should be understood as one, he was formally expelled from the Jewish community. Uncertain what to make of his theological views, Jewish and Christian religious authorities alike decided that he was either a pantheist or an atheist -- and, in either case, anathema. Widely banned, his writings went underground, where they were translated into several languages and disseminated across Europe. The dangerous doctrine that came to be known as "Spinozism" left a colossal footprint on the Enlightenment, and on modern sensibilities more broadly.

The significance of this way of thinking "as an early forerunner of quintessentially modern modes of religious doubt and rebellion has seldom been acknowledged" in the historiographical literature, Mr. Sutcliffe writes. Standard accounts of the Enlightenment have tended to locate the main action either in Paris (around the philosophes), or in Germany (around Kant and the Kantians), or in the English-Scottish matrix. This understanding received major corrective surgery in Jonathan I. Israel's Radical Enlightenment: Philosophy and the Making of Modernity, 1650-1750 (Oxford University Press, 2001), which focused a zoom lens on 17th-century Sephardic Amsterdam and the transnational influence of Spinoza's circle. (Mr. Israel was Mr. Sutcliffe's professor at University College London and supervised his dissertation, on which Judaism and Enlightenment is based.)

The Enlightenment dream of a world without myth contained severe internal contradictions, Mr. Sutcliffe argues. Which is why Pierre Bayle (1647-1706) is one of his "favorite characters" in the book. Bayle, he writes, provided "the most inclusive and the most philosophically rigorous argument for toleration" in his time, "confronting the dilemmas of the concept more directly than any other Enlightenment writer." Against the grain of what Mr. Sutcliffe calls "rationalist absolutism," Bayle, a member of the French Huguenot community persecuted as a religious minority and exiled to Holland, held that the principle of toleration could not, in the end, be grounded on abstract arguments alone. Seeing the "paradoxical insufficiency of reason" as the basis for moral principles, Bayle, a "lover of paradox," Mr. Sutcliffe writes, instead appealed to faith as the basis for toleration.

Progress or Regress?

If the early Enlightenment was characterized by a consuming preoccupation with Judaic themes, marked by deep ambivalence, later Enlightenment thinkers were decidedly less equivocal in their regard for Judaism. The pre-eminent figure of the 18th-century Enlightenment, Voltaire, was all but consumed with enmity toward Judaism. No fewer than a third of the entries in his Philosophical Dictionary were devoted to deriding and vilifying the Jews.

This is not insignificant for Mr. Sutcliffe: "Far from being a quirk of his personal biography or temperament, Voltaire's persistent hostility towards Judaism in a sense draws into unique focus the problems underlying the general Enlightenment stance toward a minority that appeared profoundly unassimilable to its logic." The historian points out that in Voltaire's myriad pronouncements on matters Jewish, he repeatedly contradicts himself.

He claims, on the one hand, that the Jews are insignificant. In his writings on the philosophy of history, for example, he insists that Jewish contributions to civilization have been vastly overrated. Yet he keeps coming back to the subject -- he just can't seem to leave it alone.

"Despite his professed desire to dismiss the Jews as a historical irrelevance and a cultural embarrassment," Mr. Sutcliffe writes, "Jews populate his writings more ubiquitously than any other people."

The Enlightenment's Jewish preoccupation transcended the realm of pure intellectual argument, Mr. Sutcliffe says. The Constituent Assembly of the French Revolution spent a striking amount of time deliberating what to do about the Republic's Jews. "Despite the immensely crowded agenda facing the revolutionaries between 1789 and 1791, they repeatedly and vociferously debated the appropriate status of the approximately 40,000 Jews of France, while utterly ignoring, for example, the question of the rights of women."

There's a reason, in Mr. Sutcliffe's view, that Judaism got under the skin of the rationalists: It symbolized the persistence of the mythical, a realm that Enlightenment thinkers wanted to conquer once and for all by means of Reason, but which stubbornly remained impermeable to Reason's jurisdiction. The mythical just did not give in to Reason's demands, and the continued presence of the archaic Jewish tradition served as an unpleasant reminder of that fact -- a thorn in the side of the Enlightenment's Dream of Reason.

Judaism thus preoccupied Voltaire, Mr. Sutcliffe contends, "because it encapsulates the residuum of myth and tradition that is impervious to his Enlightenment critique."

And the prospect of a world without myth is neither possible nor desirable, Mr. Sutcliffe argues: "We need both reason and myth." The "mythic resilience" of Judaism calls attention to the limits of the Enlightenment. "Enlightenment fundamentalism," Mr. Sutcliffe says, can distort our understanding of the Other, or that which we deem to be irrational.

Mr. Sutcliffe thus sees his book as more than a contribution to intellectual history. It is also a philosophical argument, he says, a cautionary tale against what he calls "the seductions of rationalist absolutism."