and the message. The use of any kind of medium or extension of man alters the patterns of interdependence among people, as it alters the ratios among our senses. It is a persistent theme of this book that all technologies are extensions of our physical and nervous systems to increase power and speed. Again, unless there were such increases of power and speed, new extensions of ourselves would not occur or would be discarded. For an increase of power or speed in any kind of grouping of any components whatever is itself a disruption that causes a change of organization. The alteration of social groupings, and the formation of new communities, occur with the increased speed of information movement by means of paper messages and road transport. Such speed-up means much more control at much greater distances. Historically, it meant the formation of the Roman Empire and the disruption of the previous city-states of the Greek world. Before the use of papyrus and alphabet created the incentives for building fast, hard-surface roads, the walled town and the city-state were natural forms that could endure. Village and city-state essentially are forms that include all human needs and functions. With greater speed and, therefore, greater military control at a distance, the city-state collapsed. Once inclusive and self-contained, its needs and functions were extended in the specialist activities of an empire. Speed-up tends to separate functions, both commercial and political, and acceleration beyond a point in any system becomes disruption and breakdown. So when Arnold Toynbee turns, in A Study of History, to a massive documentation of "the breakdowns of civilizations," he begins by saying: "One of the most conspicuous marks of disintegration, as we have already noticed, is ... when a disintegrating civilisation purchases a reprieve by submitting to forcible political unification in a universal state." Disintegration and reprieve, alike, are the consequence of ever faster movement of information by couriers on excellent roads.