Arthur Schopenhauer (1788-1860) was a German philosopher best known for his work The World as Will and Representation. He responded to and expanded upon Immanuel Kant's philosophy concerning the way in which we experience the world. His critique of Kant, his creative solutions to the problems of human experience and his explication of the limits of human knowledge are among his most important achievements. His metaphysical theory is the foundation of his influential writings on psychology, aesthetics, ethics, and politics which influenced Friedrich Nietzsche, Wagner, Ludwig Wittgenstein, Sigmund Freud and others. He said he was influenced by the Upanishads, Immanuel Kant, and Plato. References to Eastern philosophy and religion appear frequently in his writing. He appreciated the teachings of the Buddha and even called himself a Buddhaist. He said that his philosophy could not have been conceived before these teachings were available. He called himself a Kantian. He formulated a pessimistic philosophy that gained importance and support after the failure of the German and Austrian revolutions of 1848.