Great cities send you a message in a hundred subtle ways: you could do more; you should try harder. New York says you should be richer. Cambridge says you should be smarter. Silicon Valley says you should be more powerful — what matters there is how much effect you have on the world.

Practically every fifteenth-century Italian painter you've heard of was from Florence, even though Milan was just as big. Someone born in Milan must have had Leonardo's natural ability — and we've never heard of him. If even a Milanese Leonardo couldn't beat the force of environment, do you suppose you can?

Berkeley turned out not to be Cambridge with good weather. The message Berkeley sends is: you should live better. Cambridge with good weather isn't Cambridge — the people there are selected by the willingness to endure an expensive, grubby place with bad weather just to be where the smartest people are.

There's an asymmetry between encouragement and discouragement like the asymmetry between gaining and losing money. Plenty of people are strong enough to resist doing what a city expects of them, but few are strong enough to keep working on something no one around them cares about.

A city speaks to you mostly by accident — in things you see through windows, in conversations you overhear. A friend said the worst thing about Silicon Valley was the low quality of the eavesdropping. The conversations you overhear tell you what sort of people you're among.

New York is unlikely to rival Silicon Valley as a startup hub because someone starting a startup there would feel like a second-class citizen — professors in NY and the Bay Area are second-class citizens until they start hedge funds or startups respectively. Each city focuses on one type of ambition because admiration is zero-sum.

On why ambitions are incompatible within a city.

One sign of a city's potential as a technology center is the number of restaurants that still require jackets for men. Zagat lists none in San Francisco, LA, Boston, or Seattle, but 13 in New York and 20 in Paris. If you walk into a fancy SF restaurant in jeans and a t-shirt, they're nice to you — who knows who you might be? Not in New York.

In most ambitious kids, ambition precedes anything specific to be ambitious about — they know they want to do something great but haven't decided whether it's rock star or brain surgeon. So you'll probably have to find the city where you feel at home to know what sort of ambition you have.