centralism and explosion of functions, and not implosion, contraction or simultaneity. An airline executive who is much aware of the implosive character of world aviation asked a corresponding executive of each airline in the world to send him a pebble from outside his office. His idea was to build a little cairn of pebbles from all parts of the world. When asked, "So what?" he said that in one spot one could touch every part of the world because of aviation. In effect, he had hit upon the mosaic or iconic principle of simultaneous touch and interplay that is inherent in the implosive speed of the airplane. The same principle of implosive mosaic is even more characteristic of electric information movement of all kinds. Centralism and extension of power by wheel and written word to the margins of empire are creative of the direct force, outside and external, to which men do not necessarily submit their minds. But implosion is the spell and incantation of the tribe and the family, to which men readily submit. Under technological explicitness, even of the urban centralist structure, some men managed to break out of the charmed circle of tribal magic. Mumford cites the words of the Chinese philosopher Mencius as a comment on this situation: When men are subdued by force they do not submit in their minds, but only because their strength is inadequate. When men are subdued by power in personality they are pleased to their very heart's core and do really submit. As the expression of new specialist extensions of our bodies the congregating of people and supplies in centers by wheel and road called for endless reciprocal expansion in a spongelike action of intake and output, which has entrapped all urban structures everywhere in place and time. Mumford observes: "If I interpret the evidence correctly, the cooperative forms of urban