In his ground-breaking and still widely disputed account of the ‘Radical Enlightenment’, Jonathan Israel recounts the story of the epochal transformation of Western civilisation beginning around the 1650s, when ‘a general process of rationalization and secularization set in which rapidly overthrew theology's age-old hegemony in the world of study, slowly but surely eradicated magic and belief in the supernatural from Europe's intellectual culture, and led a few openly to challenge everything inherited from the past’. Yet, notwithstanding its centrality to the ‘making of modernity’, the historical dimension of the Enlightenment in Israel's view ‘continues to be very inadequately understood and described’.

Whether Israel actually undertook a genuinely historical investigation of the Enlightenment, or he pursued instead an ideological agenda aimed to reassert the primacy of modern Western liberal and democratic ideals, is a question that remains highly controversial. While it is not the purpose of the present book to take sides in this scholarly controversy, nonetheless it takes on Israel's call for the importance of conducting new research on the ‘historical dimension’ of the Enlightenment as key to the serious understanding of such a movement. As Darrin McMahon has effectually pointed out, Israel's apparently contradictory statement originates from the ‘ambiguity inherent in the very word enlightenment’, which is widely used to refer both to the ‘still unfolding process of modernity’ and ‘to the historical movement that gripped Europe and the Americas in the late seventeenth century and the eighteenth’.