In our American cities, we need all kinds of diversity.

I think it is fatal to specialize. And all kinds of things show us that and that the more diverse we are in what we can do, the better.

My mother used to say when we were children, 'When a boy gets a stick in his hand, his brains run out the other end of it.' Power is a stick in the hand, and I have never heard of anybody who wielded a very big stick of power whose brains did not run out the other end. As a nation, our brains are running out the other end of our power right now.

The more successfully a city mingles everyday diversity of uses and users in its everyday streets, the more successfully, casually (and economically) its people thereby enliven and support well-located parks that can thus give back grace and delight to their neighborhoods instead of vacuity.

But look what we have built low-income projects that become worse centers of delinquency, vandalism and general social hopelessness than the slums they were supposed to replace. Cultural centers that are unable to support a good bookstore. Civic centers that are avoided by everyone but bums. Promenades that go from no place to nowhere and have no promenaders. Expressways that eviscerate great cities. This is not the rebuilding of cities. This is the sacking of cities.

When we deal with cities we are dealing with life at its most complex and intense. Planners are guided by principles derived from the behaviour and appearance of suburbs, tuberculosis sanatoria, fairs and imaginary dream cities - from anything but cities themselves.

You don't get new products and services out of sameness.