Friedrich Nietzsche (1844–1900) was a German philosopher, a cultural critic, and a philologist who published intensively in the 1870s and 1880s. His work has exerted a profound influence on modern intellectual history for its uncompromising criticism of traditional European morality and religion, as well as of the conventional philosophical ideas and social and political pieties associated with modernity. He began his career as a classical philologist before turning to philosophy. Much of his criticism relies on psychological diagnoses that exposes false consciousness infecting people’s received ideas. Nietzsche's writing spans philosophical polemics, poetry, cultural criticism, and fiction while displaying a fondness for aphorism and irony. Prominent elements of his philosophy include his radical critique of truth in favor of perspectivism; a genealogical critique of religion and Christian morality and a related theory of master–slave morality; the aesthetic affirmation of life in response to both the "death of God" and the profound crisis of nihilism.