conscripting their subjects and severely constrained their ability to raise taxes. The impact of wars on civilian populations was in no way comparable to the horrors of the Thirty Years’ War or what technology and ideology would produce two centuries later. In the eighteenth century, the balance of power operated as a theater in which “ lives and values were put on display , amid splendor, polish, gallantry, and shows of utter self-assurance.” The exercise of that power was constrained by the recognition that the system would not tolerate hegemonic aspirations.
International orders that have been the most stable have had the advantage of uniform perceptions. The statesmen who operated the eighteenth-century European order were aristocrats who interpreted intangibles like honor and duty in the same way and agreed on fundamentals. They represented a single elite society that spoke the same language (French), frequented the same salons, and pursued romantic liaisons in each other’s capitals. National interests of course varied, but in a world where a foreign minister could serve a monarch of another nationality (every Russian foreign minister until 1820 was recruitedabroad), or when a territory could change its national affiliation as the result of a marriage pact or a fortuitous inheritance, a sense of overarching common purpose was inherent. Power calculations in the eighteenth century took place against this ameliorating background of a shared sense of legitimacy and unspoken rules of international conduct.
This consensus was not only a matter of decorum; it reflected the moral convictions of a common European outlook. Europe was never more united or more spontaneous than during what came to be perceived as the age of enlightenment. New triumphs in science and philosophy began to displace the fracturing European certainties of tradition and faith. The swift advance of the mind on multiple fronts—physics, chemistry, astronomy, history, archaeology, cartography, rationality—bolstered a new spirit of secular illumination auguring that the revelation of all of nature’s hidden mechanisms was only a question of time. “The true system of the world has been recognized, developed, and perfected,” wrote the brilliant French polymath Jean Le Rond d’Alembert in 1759, embodying the spirit of the age:
In short, from the earth to Saturn , from the history of the heavens to that of insects, natural philosophy has been revolutionized; and nearly all other fields of knowledge have assumed new forms … [T]he discovery and application of a new method of philosophizing, the kind of enthusiasm which accompanies discoveries, a certain exaltation of ideas which the spectacle of the universe produces in us—all these causes have brought about a lively fermentation of minds. Spreading through nature in all directions like a river which has burst its dams, this fermentation has swept with a sort of violence everything along with it which stood in its way.
This “fermentation” based itself on a new spirit of analysis and a rigorous testing of all premises. The exploration andsystematization of all knowledge—an endeavor symbolized by the twenty-eight-volume
Encyclopédie
that d’Alembert co-edited between 1751 and 1772—proclaimed a knowable, demystified universe with man as its central actor and explicator. Prodigious learning would be combined, d’Alembert’s colleague Denis Diderot wrote, with a “ zeal for the best interests of the human race .” Reason would confront falsehoods with “ solid principles [to] serve as the foundation for diametrically opposed truths,” whereby “we shall be able to throw down the whole edifice of mud and scatter the idle heap of dust” and instead “put men on the right path.”
Inevitably, this new way of thinking and analysis was applied to concepts of governance, political legitimacy, and international order. The political philosopher Charles-Louis de Secondat,