To learn using metaphors, take a system you understand and fit it into a complicated natural system. For example, you notice that the organization of a city is similar to a person's blood vessels. The streets are the vessels. The buildings are the cells. The cars are the blood cells.
Once you have the foundation laid, look for components in either system that haven't been matched up yet. Often you'll discover a component in one system that leads you to discover for the first time the matching component in the other system. The blood system has white blood cells. These correspond to police vehicles and tow trucks, and like white blood cells they are usually travelling along with the rest of the cars in case they are needed. The people in the cars are the oxygen and other materials that the blood cells carry to the cells.
You may also notice things that don't match up but that'll still lead to learning about the two systems. For example, while cities have traffic lights, two-way streets, and criss-crossing traffic, the blood system doesn't really have equivalents of these. Why is that? It's because the task of the blood system is to move objects along a known path from the lungs, to the heart, and through a capillary somewhere and back. A city's streets on the other hand must transfer cars from any arbitrary point in the city to any other arbitrary point. So, you've come to an abstract understanding of the task that each system solves. Based on that, you realize that the roads in most airports and fast-food drive throughs are more like that of the a blood system because their task is more linear and set.
Another metaphor is the way that cities are much like the non-vascular plants that grow flat on the surface of rocks and other things. Originally, there were only non-vascular plants, that could only grow to be about an inch tall because they had no central vascular system that could pump materials higher. Probably due to overcrowding, plants evolved to vascular forms that had a long stem that led to leaves and other things at the top, higher up in the sunlight.
So, we could say that most of a city is like a non-vascular plant in that it is constrained to grow on the surface and in two dimensions. Sky rises are more like vascular plants and are only viable because of their extensive elevator systems, the city equivalent of the vascular tube. A development we haven't seen yet but can expect in cities is high-rises that lead to a large top that overhangs the rest of the city, like a mushroom. We haven't seen this yet for legal reasons of who's "on" what land, perceived safety reasons, and because these "mushroom" buildings would block out the Sun for other buildings most of the day.
Another future development that would model plants' evolution would be extensive multi-tiered city streets. Rather than coping with traffic by making streets wider, cities will eventually be forced to make streets have multiple layers with many access lanes that lead between the layers. This would be similar to the cell layering that many advanced non-vascular plants have.
February 10, 2003