Arthur Schopenhauer is considered one of the most important philosophers of the 19th century. In 1818, Schopenhauer published his most famous work, "The World as Will and Representation" ("Die Welt als Wille und Vorstellung"), which presented a comprehensive philosophical system that combined elements of Kantian idealism with Eastern philosophical ideas, particularly those from Hindu and Buddhist traditions. Schopenhauer argued that the fundamental reality of the world is not the external world as it appears to us but an underlying "will," a blind and irrational force driving all human desires and actions. He is best known for his profound contributions to metaphysics, ethics, and aesthetics, as well as for his pessimistic philosophy of life.