Spencer, Herbert (1820-1903), was an English philosopher. He attempted to work out a comprehensive philosophy based on the scientific discoveries of his day. Spencer was greatly influenced by the English naturalist Charles Darwin. He applied his own and Darwin's fundamental law--the idea of evolution (gradual development)--to biology, psychology, sociology, and other fields. Spencer's major works include First Principles (1862) and Principles of Ethics (1879-1893).