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.

Power is supposed to be so corrupt. I don't think it's so much corrupt, in the usual sense of the word, as stupid and unrealistic. The more power a person has, the further he gets from reality.

New ideas often need old buildings.

Backward cities, or younger cities, or newly forming cities in supply regions, have to develop to a great extent on one another's shoulders. This is one of the terrible things about empires.

To seek "causes" of poverty in this way is to enter an intellectual dead end because poverty has no causes. Only prosperity has causes.

By its nature, the metropolis provides what otherwise could be given only by traveling; namely, the strange.

I get absolutely ruthless in my own way about not doing anything else when I am trying to concentrate on writing a book. I have to stick to it and concentrate.