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.

Does anyone suppose that, in real life, answers to any of the great questions that worry us today are going to come out of homogeneous settlements?

Some men tend to cling to old intellectual excitements, just as some belles, when they are old ladies, still cling to the fashions and coiffures of their exciting youth.

Cities need old buildings so badly it is probably impossible for vigorous streets and districts to grow without them.... for really new ideas of any kind--no matter how ultimately profitable or otherwise successful some of them might prove to be--there is no leeway for such chancy trial, error and experimentation in the high-overhead economy of new construction. Old ideas can sometimes use new buildings. New ideas must use old buildings.

Cities have the capability of providing something for everybody, only because, and only when, they are created by everybody.

Nothing is so clear in history that is it happens for any one thing. It seems that a lot of things come together to make great changes.

poverty has no causes. Only prosperity has causes. Analogically, heat is a result of active processes; it has causes. But cold is not the result of any processes; it is only the absence of heat. Just so, the great cold of poverty and economic stagnation is merely the absence of economic development.