"Kant himself says that he is drawing the limits of knowledge to make space for religious faith, but it is now pretty clear that the modern world has been unable to fill that space. In the philosophy of J. G. Fichte, F. W. J. Schelling and G. W. F. Hegel, known as 'German Idealism', which begins in the 1790s, the space is often filled with aspects of what Kant proposes which are given a more emphatic status than Kant himself thinks possible. Fichte, for example, will make the activity of the I the source of the world's intelligibility in a way that Kant rejects. Development of some of these thinkers' ideas will be germane to Schopenhauer, Ludwig Feuerbach, Marx, and Nietzsche, who, though, reject many of the central philosophical contentions of German Idealism. However, the structures which inform much of what these thinkers say still depend upon what might initially appear to be rather specialized aspects of Kant's philosophy."