The 150th anniversary of the birth of Karl Marx takes place in a setting which differs fundamentally from that in which his critical theses were worked out. These theses, from his “juvenilia” to Das Kapital—in turn celebrating its centenary—and the foundation of the International, changed the destiny of the world, of its peoples, States and nations. One is readily aware of the modifications in historical, economic, and political conditions, buffeted by revolutions and confrontation. But it is with difficulty that specialists—whether of theory or practice—take cognizance of other dimensions of this difference, which we consider to be fundamental to, and constitutive of, the very formulation of the theoretical problem which forms the subject of our study. Finally, however, the nationalitarian phenomenon asserts itself, day after day, as an objectively central factor in the multiform dialectics of revolutions, of evolutions, of counter-revolutions, and of apparent stagnation. Here a geographical thread is added to the historical one. But this new element is not, as some would wish it, a topographical one. The aim of the geographical dimension, or rather that of historical geography, is not to accommodate the geopolitical analysis of the contemporary world, but to serve as a framework for the emergence on the sociological level of a key concept, that of civilization, which seems to us to be necessary in order to determine the general theoretical pattern of the evolutionary process of human societies in this time of ours, the second half of the twentieth century.