https://www.d.umn.edu/cla/faculty/jhamlin/4111/MarxReadings/Estranged Labour, Marx, 1844.htm

Every self-estrangement of man from himself and nature is manifested in the relationship he sets up between other men and himself and nature. Thus, religious self-estrangement is necessarily manifested in the relationship between layman and priest, or, since we are dealing here with the spiritual world, between layman and mediator, etc. In the practical, real world, self-estrangement can manifest itself only in the practical, real relationship to other men. The medium through which estrangement progresses is itself a practical one. So through estranged labour man not only produces his relationship to the object and to the act of production as to alien and hostile powers; he also produces the relationship in which other men stand to his production and product, and the relationship in which he stands to these other men. Just as he creates his own production as a loss of reality, a punishment, and his own product as a loss, a product which does not belong to him, so he creates the domination of the non-producer over production and its product. Just as he estranges from himself his own activity, so he confers upon the stranger and activity which does not belong to him.