Spencer developed an all-embracing conception of evolution as the progressive development of the physical world, biological organisms, the human mind, and human culture and societies. As a polymath, he contributed to a wide range of subjects, including ethics, religion, anthropology, economics, political theory, philosophy, literature, astronomy, biology, sociology, and psychology. During his lifetime he achieved tremendous authority, mainly in English-speaking academia. Spencer was "the single most famous European intellectual in the closing decades of the nineteenth century" but his influence declined sharply after 1900: "Who now reads Spencer?" asked Talcott Parsons in 1937.
