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

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.

Evolution continually innovates, but at each level it conserves the elements that are recombined to yield the innovations.

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

When a new building block is discovered, the result is usually a range of innovations.

Model building is the art of selecting those aspects of a process that are relevant to the question being asked. As with any art, this selection is guided by taste, elegance, and metaphor; it is a matter of induction, rather than deduction. High science depends on this art.

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