forms of transport of goods and information, both as 
metaphor and exchange. Each form of transport not only 
carries, but translates and transforms, the sender, the receiver, 
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