(October 15, 1844 August 25, 1900), was a German philosopher. He wrote critiques of religion, morality, contemporary culture, philosophy, and science, using a distinctive style and displaying a fondness for aphorism. Nietzsche's influence remains substantial within and beyond philosophy, notably in existentialism and postmodernism. His style, and radical questioning of the value and objectivity of truth, raise considerable problems of interpretation, generating an extensive secondary literature in both continental and analytic philosophy. Nonetheless, his key ideas include interpreting tragedy as an affirmation of life, an eternal recurrence that has fallen into numerous interpretations, a reversal of Platonism, and a repudiation of Christianity as it was in the 19th century.