Germany's influence on philosophy is historically significant and many notable German philosophers have helped shape western philosophy since the Middle Ages. Gottfried Leibniz's contributions to rationalism; the establishment of classical German idealism by Immanuel Kant, Georg Wilhelm Friedrich Hegel, Friedrich Wilhelm Joseph Schelling and Johann Gottlieb Fichte; Karl Marx's and Friedrich Engels' formulation of Communist theory; Arthur Schopenhauer's composition of metaphysical pessimism; Friedrich Nietzsche's development of Perspectivism; Martin Heidegger's works on Being; and the social theories of Jürgen Habermas were especially influential.
German literature can be traced back to the Middle Ages and the works of writers such as Walther von der Vogelweide and Wolfram von Eschenbach. Various German authors and poets have won great renown, including Johann Wolfgang von Goethe and Friedrich Schiller. The collections of folk tales published by the Brothers Grimm popularised German folklore on an international level. Influential authors of the 20th century include Thomas Mann, Berthold Brecht, Hermann Hesse, Heinrich Böll, and Günter Grass.
