Each civilization that has left legible records or significant traditions during the past five or six thousand years has made distinctive contributions that modified the culture pattern of its predecessors and its contemporaries. At the same time all of the civilizations have had certain common features that are the characteristic aspects which justify the general definition of civilization presented in the Introduction to this study. Civilization is the most comprehensive, extensive and inclusive life pattern achieved by terrestrial humanity. Starting locally and following the three basic principles of urbanization, expansion and exploitation, each civilization has charted a course that led from tentative local beginnings through a cycle of growth, maturity, decline, decay and dissolution. The civilizing process is essentially collective, subordinating the interests of each part to the interests of the whole, while allowing sufficient home rule to enable each part to have the political, economic and cultural advantages enjoyed by the other parts, always excepting the privileged position occupied by the civilization's dominant empire and its nucleus. Necessarily a civilization is composed of more or less disparate segments, each one (before its inclusion in the collective whole) maintaining a large measure of sovereign independence. Utilizing advanced techniques of communication, exchange, and transportation, the separate sovereign units are coordinated, consolidated, unified and universalized. The result is an aggregate of parts, differing in many local respects, but acknowledging the authority of the power center and contributing material goods and manpower to its support and defense. The main sociological purpose of each civilization has been to impose central authority and universality upon political, economic and ideological diversity. Every civilization has been confronted with the advantages of unity over diversity. Every civilization has professed its devotion to unity. Every civilization at one or another stage in its development has subordinated unity to the increasingly insistent demands of diversity. For at least six thousand years one civilization after another has sought to achieve centralization and universality. In every instance of which history provides a legible record, centralized, universalized institutions and practices have fragmented into diversity and stubborn localism.