Hobbes’s Kingdom of Light is a wide-ranging exploration of Hobbes’s thought. The book delves into Hobbes’s critique of the classical tradition, his natural philosophy, and his critique of religion before turning to his more familiar political philosophy. By considering neglected aspects of Hobbes’s thought as well as its more famous features, the book brings out the breadth and complexity of Hobbes’s revolutionary war against the “Kingdom of Darkness.” Hobbes was engaged in a struggle on multiple fronts against forces, both philosophic and religious, that he thought had long distorted philosophy and destroyed the prospects of a lasting peace in politics. By exploring the twists and turns of Hobbes’s own arguments, not only in his famous Leviathan but throughout his corpus, the book uncovers the details of Hobbes’s critique of an older outlook, rooted in classical philosophy and Christian theology, as well as the key features of the new outlook—the “Kingdom of Light”—that Hobbes sought to put in its place. Hobbes’s venture helped to prepare the way for the later emergence of modern liberalism and modern secularism. The close examination and careful evaluation of that venture sheds new light on the origins of principles and movements that are at once ascendant and beleaguered today.