Paralleling their domestic expansion, civilizations expand geographically up to the point of diminishing returns, determined by the growth of overhead costs.  This process has taken the civilization, its personnel, its institutions and practices into territory not heretofore occupied, sometimes with the consent of the “foreigners”, but more often in the teeth of their determined and long-continued opposition.

Expansion of a civilization is of necessity a movement from an urban center and beyond the urban center.  Each civilization has been built around one or more urban nuclei which accepted and practiced expansion as the primary law of their beings.

Expansion takes many forms.  It may be peaceful, as travel is peaceful.  It may be competitive, as trade is competitive.  It may be economically aggressive; the search for markets, for raw materials, for investment opportunities carried on simultaneously by representatives of long time rival cities, states, empires.  It may be a movement for a place in the sun; mass migration, colonization.  It may take the form of planned military invasion having as its purpose the conquest and occupation of foreign territory; the subjugation of the citizenry of the conquered lands; the establishment of an alien government in the conquered territory; the reduction of the “natives” to the status of second class citizens in their own homelands; exploitation of the natural resources; the levying of tribute; the imposition of taxes and the expropriation of moveable articles such as bullion, works of art and other treasure by the invaders, conquerors and occupiers.

Policies of expansion, conquest and occupation rely upon weaponry and war-making as essential instruments.  Historically their role has been frankly recognized by builders of every empire and the leaders of every civilization.  All civilizations known to history prepared for war and utilized war as the final arbiter in their pursuit of expansionist policy.  Empire builders and civilizers have taken it for granted that might made right.  The mighty, in terms of military striking power and killing power, have fought over and inherited the earth.

The practices of every civilization have centered about exploitation—­of natural resources, of labor power, of rivals in the race for supremacy, of weaker and less aggressive peoples.  Expansion gives the ruling oligarchy of the expanding nation, empire or civilization command of the strategic vantage points from which the principle of exploitation can be made continuously operative.

We have dealt with exploitation in connection with the economics of civilization (Chapter 7).  Its central concept is the “you work—­I eat” formula.  In sociological terms it extends far beyond livelihood, into the relations of man with the natural environment (ecology); the management and direction of labor power and policy making; social administration and policy implementation, including policing of the territories lying within the frontiers of the nation, empire or civilization, plus contacts and relationships with territories lying outside the frontiers:  in short, with the success or failure, the domination or subordination of the territory under consideration.