"Where will you get a conception of society and progress in general if you have not studied a single social formation in particular, if you have not even been able to establish this conception, if you have not even been able to approach a serious factual investigation, an objective analysis of social relations of any kind? This is a most obvious symptom of metaphysics, with which every science began: as long as people did not know how to set about studying the facts, they always invented a priori general theories, which were always sterile." - What the “Friends of the People” Are and How They Fight the Social-Democrats (1894)