 Thomas Hill Green (1836–82) is widely regarded as the founding and most influential figure in the tradition of British idealism that flourished in England, especially Oxford, and Scotland, especially Glasgow and Edinburgh, in the second half of the nineteenth century and early in the twentieth century (see, e.g., Mander 2011). Green’s idealism was systematic, embracing metaphysics and epistemology, ethical theory, political philosophy, and philosophy of history and religion. In metaphysics and epistemology, Green reflected the influence of Immanuel Kant, criticizing the British empiricist legacy of John Locke and David Hume. Green argued that empirical knowledge is the workmanship of the human mind, that reality depends on thought and cannot transcend it, and that the possibility of objectivity requires the existence of a single corporate or divine consciousness of which individual minds are proper parts. The only defensible form of idealism, Green thought, is absolute idealism, in which all aspects of reality are operations of a single consciousness. In ethics, Green embraced a form of perfectionism that identifies the human good with self-realization and the perfection of our nature as moral persons and agents. But self-realization must reflect the way in which individuals participate in associations and communities and, as a result, must reflect the demand that individuals pursue a common good. In articulating this conception of perfectionism, Green sees himself as synthesizing the best elements in two different ethical traditions—Greek eudaimonism and Kantian rationalism. Green’s perfectionist ethics influence his politics. He provides the philosophical foundations for a new progressive form of liberalism that transcends the laissez-faire liberalism characteristic of some strands in nineteenth century British liberalism. The state has a duty to promote the common good, and individual rights are constrained by the common good. This gives the state not just negative duties to refrain from interfering with the freedoms and opportunities of its citizens but also positive duties to provide resources and opportunities for individual self-realization. The ethical and political demand for self-realization, Green thinks, is freedom, properly understood. He believes that moral and political progress in history consists in the gradual and increasingly more adequate realization of the values of perfection, the common good, and freedom. Because Green identifies God with the metaphysical, ethical, and political principles in human nature, he sees God as immanent in the progressive developments in human history.