Possibly one of the reasons for the oft-repeated urban cycle of growth, expansion, and disintegration...lies in the very nature of civilization itself. We have seen that in many instances the city tends to encase the organic, many-sided life of the community in petrified and overspecialized forms that achieve continuity at the expense of adaptation and further growth. The very structure of the city itself, with the stone container dominating the magnet, may in the past have been in no small degree responsible for this resistance. In the end it has made physical disintegration--through war, fire, or economic corrosion and blight--the only way of opening the city up to the fresh demands of life.
Lewis Mumford, The City In History, p. 526