This work first tried (perhaps in rivalry with the Owens utopian movement) to set the fall of matriarchy as the origin of all class society. Engels' work follows Marx's lead in the study of Lewis H. Morgan's Ancient Society Or Researches In The Lines Of Hum an Progress From Savagery, Through Barbarism To Civilization, (New York, 1877), considering societies based on class and property as developing materialistically from origins based on sexual ties and the inevitable disharmony of the two social states. Engels credits Morgan with "finding in the sexual organizations of the North American Indians the key that opens all the unfathomable riddles of most ancient Greek, Roman and German history." Engels extends Morgan's "epochal" work to German and Celtic application. Attention is paid to the role of the family in primitive society, barbarism and civilization, the various schools and trends with respect to the concept of social stages, the forms of property kinship and marriage, and the subjugation of women in relation to the emergence of private property classes and state Book jacket.