Why do sociologists today still refer to Marx so often? Well in first place because he brought something to light that we still try to fully comprehend. His important idea that human beings are not a collection of abstractions living on the inside of every individual body. But that they are in actual fact the ensemble, the totality of all the social relationships that tie them together. This is an idea that 27 years old Carl Marx scribbled down in 1845 as one of his [FOREIGN] on the philosopher, Feuerbach. You may remember his famous Eleventh Thesis on Feuerbach, where Marx says that the philosophers have only interpreted the world in many different ways but that now the time has come that we should actually try to change the world. But I really believe that thesis number six is more important because that is where he says that the essence of the human being is not located in her or his individuality within the social network of which she or he is a part. This is an idea that Marx in one of his later books, formulated in a sentence that became very famous, it is not the consciousness of men that determines their being, but, on the contrary, their social being that determines their consciousness. What people think is influenced by the social context of which they are part and this idea has given rise to some of the most important branches of sociological research. The way, for example, in which the social context influences the artistic impulses products of human beings. That is studied in the sociology of art, the sociology of literature, the sociology of music, even in the sociology of the cinema. How those social surroundings may influence behavior that is in a certain society considered punishable. That is studied by the sociology of law and also by the sociology of deviant behavior, and the sociology of crime or criminology. How those social structures may influence our belief systems is studied by the sociology of religion. And the social influences on how people think, how they reason, is studied by a very important subdiscipline called the sociology of knowledge. And I could go on and on with this list, making it longer and longer, but let me mention one more. Today, we do not believe anymore that scientific thought develops in a social vacuum. We now can see that even in science, the flow of ideas is influenced by social developments. And this is the intriguing field of study that is called the sociology of science. So, how people think and feel and act is profoundly influence by the social networks in which they are enveloped, so to say. Maybe I should say the networks that they are. And that is an extremely fruitful insight, something that became the cornerstone in the sociologies of Emile Durkheim and of Norbert Elias. But then Marx narrows it down a bit, because he believes that the most important interdependencies between human beings are those having to do with survival. For example, the gathering of the food that you need in order to stay alive. Dividing the economic tasks in such a clever way that the group, the collectivity may live and procreate the networks that people form when they wrestle from their surrounding nature, the essentials that they need in order to survive. Our gold, in Marxian terminology, the productive relations, [FOREIGN]. They are very fundamental. The other relationships between people, for example their cognitive ties or their political relations, are all derived from what is at the heart of it all, their economic chains of interdependence. Another way of expressing this is that the infrastructure, that is the economic base of society, determines the superstructure that contains politics, law, religion, the arts, the sciences. Marx wrote those things, of course, in the German language. And there he wrote about unterbau and uberbau. That, in fact, is an architectural metaphor. The unterbau, that's the part of a house that is hidden underground. You don't see it, but it is the foundation of the building. What you do see is the uberbau. The walls, the front door, the windows, the roof. But if you want to buy that house, you are well advised not to pay too much attention to what catches the eye, but to take the little staircase into the cellar under the house, and try to see if there are little cracks in the walls that may predict the collapse of the whole construction in the future. If you want to investigate the strength of a society, don't look at the things that are easy to notice, Marx tell his readers. The beautiful artwork, the great universities, the inviting avenues, the smart political debates. No, you should try to see what goes on in the less visible economic basement of that society. Because the eventual collapse of the whole system may be visible when you study the contradictions and the oppositions that already today strike the eye of anyone who is trained to study the economic undercurrents.