And the more complicated, multilingual, multicultural, wildly diverse the city, the greater its output of new ideas. “What drives a city’s innovation engine, then—and thus its wealth engine—is its multitude of differences,” says Stewart Brand. In fact, Santa Fe Institute physicist Geoffrey West found that when a city’s population doubles, there is a 15 percent increase in income, wealth, and innovation. (He measured innovation by counting the number of new patents.)
