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.

The entrepreneurial investors of the time just want to repeat themselves indefinitely and don't know when to stop. You can't do that. And so finally the housing boom, or the auto boom, or whatever it is that's been carrying things along, runs out of customers.

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.

The second mode to deal with unsafe cities is to take refuge in vehicles. This is the technique practiced in the big wild-animal reservations of Africa, where tourists are warned to leave their cars under no circumstances until they reach a lodge. It is also the technique practiced in Los Angeles.

[ René Lévesque] didn't understand why things do collapse. It's usually a very banal reason why things do collapse. It's not a grand reason, why they collapse economically, at least in the West.

All through organized history, if you wanted prosperity you had to have cities. Cities are places that attract new people with new ideas.

The point of cities is multiplicity of choice.