Among distinguished sociologists, Friedrich Engels was a German-English social scientist and father of Marxist theory, along with Karl Marx. The Condition of the Working Class in England (1845), was based on personal observations and research, a description of working-class life in industrializing England. In 1848 Friedrich Engels co-authored The Communist Manifesto (1848) with Karl Marx, and also helped Marx financially to do research and write Das Kapital.
Friedrich Engels organized Marx's notes on the "Theories of Surplus Value" published as the "fourth volume" of Capital. Friedrich Engels' and Marx also jointly wrote The Holy Family (1845) and The German Ideology (1845). Friedrich Engels laid the foundations of dialectical materialism in Anti-Duhring (1877-8) and Dialectics of Nature (I952). Like Charles Darwin, he believed that social development followed evolutionary principles.
Friedrich Engels developed Marxism on a scientific basis, natural science being conceived as both materialistic and following dialectical laws. The Origin of the Family, Private Property and the State condemns of women's subjugation and association of patriarchy with private property is discredited.