The essay "Das Unbehagen in der Kultur," published in 1930, is one of Freud's most important works on cultural theory, along with "Mass Psychology and Ego Analysis" and the religion-critical paper "The Future of an Illusion." In the course of cultural development, interpersonal aggressions are not only suppressed but are partly transformed into a kind of guilt, the conscience, which triggers a diffuse sense of lack. In this sense, Freud understands discomfort in culture as the price paid by individuals for general cultural progress, with an expansion of feelings of guilt accompanied by an increasing loss of happiness.