The recycling of resource by the aggregate behavior of a diverse array of agents is much more than the sum of the individual actions.

If we are to understand the interactions of a large number of agents, we must first be able to describe the capabilities of individual agents.

This use of building blocks to generate internal models is a pervasive feature of complex adaptive systems.

nonlinear interactions almost always make the behavior of the aggregate more complicated than would be predicted by summing or averaging.

The multiplier effect is a major feature of networks and flows. It arises regardless of the particular nature of the resource, be it goods, money, or messages.

With theory, we can separate fundamental characteristics from fascinating idiosyncrasies and incidental features. Theory supplies landmarks and guideposts, and we begin to know what to observe and where to act.

The measure of performance of any given agent is the amount of money it accumulates through its actions.