German philosophy
Neo-Kantianism refers broadly to the revival of the type of philosophy explained by Immanuel Kant and of the interpretations of Kant provided by post-Kantian philosophers such as Schopenhauer, Jakob Friedrich Fries and Johann Friedrich Herbart. Major figures in the neo-Kantian movement, which began around the 1860s, include Friedrich Albert Lange and Hermann Cohen.
Immanuel Kant
Kant defines his theory of perception in his influential 1781 work the "Critique of Pure Reason", which has often been cited as the most significant volume of metaphysics and epistemology in modern philosophy. Kant maintains that our understanding of the external world had its foundations not merely in experience, but in both experience and "a priori" concepts, thus offering a "non-empiricist critique of rationalist philosophy", which is what has been referred to as his Copernican revolution.