One of the important—yet often underestimated—dimensions of the intellectual legacy of Isaiah Berlin is his contribution to the demystification of the totalitarian temptation in the twentieth century. This paper starts with an apparent paradox: Berlin is described as a major figure of the anti-totalitarian camp, yet his writings nowhere touch explicitly on the totalitarian regimes of his time. Nonetheless, it is argued that Berlin's notion of “monism,” and his unique insight into the totalitarian mind, are an indirect yet valuable contribution to the understanding of the appeal exercised by totalitarianism within the modern political imagination. Despite Berlin's highly contestable account of the origins of monism—which he situates in the Enlightenment movement—it is asserted that Berlin's denunciation of utopias remains very much pertinent in light of the emergence of new fundamentalist utopias in a post 9/11 world. Consequently, there are grounds from which to dismiss those claims according to which Berlin's work belongs to an age—that of the Cold War—unfamiliar to the present.