International Women's Day Greetings
What we can now conjecture about the way in which sexual relations will be ordered after the impending overthrow of capitalist production is mainly of a negative character, limited for the most part to what will disappear. But what will there be new? That will be answered when a new generation has grown up: a generation of men who never in their lives have known what it is to buy a woman’s surrender with money or any other social instrument of power; a generation of women who have never known what it is to give themselves to a man from any other considerations than real love, or to refuse to give themselves to their lover from fear of the economic consequences. When these people are in the world, they will care precious little what anybody today thinks they ought to do; they will make their own practice and their corresponding public opinion about the practice of each individual – and that will be the end of it.
Frederick Engels, Origins of the Family, Private Property and the State (1884)
Edited to add: Sally Campbell on Engels's path-breaking writings on women's liberation