Kierkegaard was one of the most original thinkers of the nineteenth century in Europe. He wrote widely on religious, philosophical, and literary themes. However, his peculiar manner of presenting some of his leading ideas initially obscured their fundamental significance. He developed his views in strong opposition to prevailing opinions, such as certain metaphysical claims about the relation of thought to existence. He reacted against the ethical and religious theories of Kant and Hegel. Moreover, he opposed the doctrines and ideas which were being advanced by some of his contemporaries like Feuerbach and Marx. His discussion of the human condition, which emphasizes the significance of individual choice, has arguably been his most striking philosophical legacy, particularly for the growth of existentialism.