Multitude is a class concept. ... Class is determined by class struggle. There are, of course, in infinite number of ways that humans can be grouped into classes - hair color, blood type, and so forth - but the classes that matter are those defined by the lines of collective struggle. Race is just as much a political concept as economic class is in this regard. ... Class is a political concept, in short, in that a class is and can only be a collectivity that stuggles in common.