Cities are not merely buildings and the spaces between them; cities are people and their networks of interaction. Cities, in other words, are society, and indeed many of society's finest attributes can be found in the city. It could, in fact, be argued that society is at its best in the city. It is the place that acts not only as the arena for society's achievements, but also enables them to come into being in the first place, by being a catalyst for them.

Cities have to rank as one of humanity's greatest achievements, but to discover how living in an urban environment can influence human activity and society we need to understand what the urban environment actually is, and to what extent it can encourage (or diminish) the scope for human flourishing.

Cities operate by making use of feedback from citizens, which creates a self-sustaining system. This is also known as autopoiesis, the capacity of a system to regenerate or repair itself, which was developed by Fritjof Capra in the 1970s as part of systems theory (Shane 2005: 55). Information flow is crucial to autopoiesis, and to the maintenance of a system's structural identity. Information flow is fed back into the system through looping mechanisms, which allows balance to be maintained. This more recent understanding of how a city operates resonates with Lewis Mumford’s argument that ‘[w]e have to stop thinking of cities as entities like trees or humans beings, which inevitably decay and die, and more like a species, which can undergo renewal and evolution’ (Mumford 1989: 3).

But what is the city? How did it come into existence? Lewis Mumford tells us that the origins of the city are obscure, but when it emerged it was already in the mature form we recognize today (1989: 4). From the beginning, the city had