古代社会
The reconstruction of the original state of primitive society or humanity was based on the idea of progress, according to which all cultures have degrees of improvement and becoming more complicated. It seemed logical to assume that never before the types of families developed did they simply exist, and in primitive society, sexual relations were without any boundaries and taboos. This view is represented, inter alia, by anthropologist Lewis H. Morgan in "Ancient Society" and quoted by Friedrich Engels' work "The Origin of the Family, Private Property and the State".