The Marxist critique sees human society in its movement, in its development in time; it utilises a fundamentally historical and dialectical criterion, that is to say, it studies the connection of events in their reciprocal interaction. Instead of taking a snapshot of society at a given moment (like the old metaphysical method) and then studying it in order to distinguish the different categories into which the individuals composing it must be classified, the dialectical method sees history as a film unrolling its successive scenes; the class must be looked for and distinguished in the striking features of this movement. In using the first method we would be the target of a thousand objections from pure statisticians and demographers (short-sighted people if there ever were) who would re-examine our divisions and remark that there are not two classes, nor even three or four, but that there can be ten, a hundred or even a thousand classes separated by successive gradations and indefinable transition zones. With the second method, though, we make use of quite different criteria in order to distinguish that protagonist of historical tragedy, the class, and in order to define its characteristics, its actions and its objectives, which become concretised into obviously uniform features among a multitude of changing facts; meanwhile the poor photographer of statistics only records these as a cold series of lifeless data. Therefore, in order to state that a class exists and acts at a given moment in history, it will not be enough to know, for instance, how many merchants there were in Paris under Louis XIV, or the number of English landlords in the Eighteenth Century, or the number of workers in the Belgian manufacturing industry at the beginning of the Nineteenth Century. Instead, we will have to submit an entire historical period to our logical investigations; we will have to make out a social, and therefore political, movement which searches for its way through the ups and downs, the errors and successes, all the while obviously adhering to the set of interests of a strata of people who have been placed in a particular situation by the mode of production and by its developments. It is this method of analysis that Frederick Engels used in one of his first classical essays, where he drew the explanation of a series of political movements from the history of the English working class, and thus demonstrated the existence of a class struggle. This dialectical concept of the class allows us to overcome the statistician’s pale objections. He does not have the right any longer to view the opposed classes as being clearly divided on the scene of history as are the different choral groups on a theatre scene. He cannot refute our conclusions by arguing that in the contact zone there are undefinable strata through which an osmosis of individuals takes place, because this fact does not alter the historical physiognomy of the classes facing one another