Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

This author suggested that there is no other road to truth except through the "brook of fire," referring to this philosopher's admiration of the writings of Ludwig Feuerbach. This author satirizes Bastiat's theory of credit as an "utter poverty of ideas under a cover of formal logic" in his Grundrisse. In addition to writing Notes on James Mill and The Civil War in France, this theorist in perhaps his most famous work claims that the constant revolutionizing of production leads to a constant disturbance of social conditions thus "all that is solid melts into air, [and] all that is holy is profaned. " Also the author of the Critique of the Gotha Program, that quote comes from a work co-written by Friedrich Engels and warns of a specter haunting Europe. FTP name this German philosopher who discussed the class struggle between bourgeoisie and the proletariat in the Communist Manifesto.
Social Science