German idealism
Neo-Kantianism refers broadly to a revived type of philosophy along the lines of that laid down by Immanuel Kant in the 18th century, or more specifically by Schopenhauer's criticism of the Kantian philosophy in his work "The World as Will and Representation" (1818), as well as by other post-Kantian philosophers such as Jakob Friedrich Fries and Johann Friedrich Herbart. It has some more specific reference in later German philosophy.
Critique of Pure Reason
The "Critique of Pure Reason" was the first of Kant's works to become famous. According to Frederick C. Beiser, the work helped to discredit rationalist metaphysics of the kind associated with Leibniz and Wolff which had appeared to provide "a priori" knowledge of the existence of God, although Beiser notes that this school of thought was already in decline by the time the "Critique of Pure Reason" was published. In his view, Kant's philosophy became successful in the early 1790s partly because Kant's doctrine of "practical faith" seemed to provide a justification for moral, religious, and political beliefs without an "a priori" knowledge of God. However, the "Critique of Pure Reason" received little attention when it was first published. Kant did not expect reviews from anyone qualified to appraise the work, and initially heard only complaints about its obscurity. The theologian and philosopher Johann Friedrich Schultz wrote that the public saw the work as "a sealed book" consisting in nothing but "hieroglyphics". The first review appeared in the "Zugaben zu den Göttinger gelehrte Anzeigen" in 1782. The review, which denied that there is any distinction between Kant's idealism and that of Berkeley, was anonymous and became notorious. Kant reformulated his views because of it, redefining his transcendental idealism in the "Prolegomena to Any Future Metaphysics" (1783) and the second edition of the "Critique of Pure Reason". The review was denounced by Kant, but defended by Kant's empiricist critics, and the resulting controversy drew attention to the "Critique of Pure Reason".