we have found new routes for understanding cities as (approximate) spatial equilibria, for deriving their structural complexity in terms of professions and neighborhoods, for understanding the first cities and their “urban package” of technologies and institutions, and for demystifying the microscopic foundations of learning

What is a complex system? By definition, a system is complex if it has emergent properties.5 I’ve already mentioned the example of the brain. We humans don’t just think – we are conscious, with a sophisticated model of ourselves, the world around us and how we fit into it. Consciousness isn’t present in the individual building blocks – it emerges