Cities never flourish alone. They have to be trading with other cities. My new hypothesis shows why. But also in trading with each other they can't be in too different stages of development, and they can't copy one another.

This is something everyone knows: A well-used city street is apt to be a safe street. A deserted city street is apt to be unsafe.

People must take a modicum of public responsibility for each other even if they have no ties to each other.

I still have a lot of family in America. I still have a lot of friends there. There is a lot that I admire there very much. When I find America getting too much criticized outside America, I want to tell them how many things are good about it.

There is no logic that can be superimposed on the city; people make it, and it is to them, not buildings, that we must fit our plans.

What if we fail to stop the erosion of cities by automobiles? ... In that case America will hardly need to ponder a mystery that has troubled men for millennia. What is the purpose of life? For us, the answer will be clear, established and for all practical purposes indisputable. The purpose of life is to produce and consume automobiles.

Lowly, unpurposeful and random as they may appear, sidewalk contacts are the small change from which a city's wealth of public life may grow.