 One device that's been very successful in history for making big changes in how we work together in groups is the startup. Just as a startup firm can do something that existing firms have great difficulty doing, a startup city, what I've called a charter city, can do something that may be very difficult to arrange in existing cities. One of the very best examples of this was the city of Shenzhen in China, which was started as a way to prototype an arrangement where foreign firms could come in, bring their technology and hire Chinese workers. The beauty of doing this in a new location and a new startup is that no one is compelled to live under the new rules. The people who moved to Shenzhen went there knowing that it would be a different kind of arrangement and they went because they believed in this model. Then when it succeeded, it was copied and led to the adoption of the market model throughout China. What cities show us is that what we've really always known, which is that we need some combination of the freedom of individual choice, of experimentation, the market incentives, within a framework that makes sure that we don't step on each other's toes, that we respect each other, that we don't cause congestion, we don't pollute, we don't infect each other with diseases. We've always known that we need some rules, some agreements on the framework, and then within that framework we can have freedom.