finance like the futures exchange or immunological networks or our own brains, highly-connected systems shared what Holland labeled an “evolving structure” - they never stayed the same. They seemed to shift, with an easy plasticity, in response to internal pressures or external changes. In the process, they took on new forms. In many cases, they became better, stronger, more adaptively fit. It wasn’t simply that the unexpected appeared, it was that the systems were evolving. We talked earlier about how political and economic ideas like serfdom or divine right fade into history as new forms - a congress, a stock market - are born to replace old ones. Holland thought the world filled with such evolutions, no different than species adjusting (or not) to a hotter climate or some fast new predator. He called the networks that produce these sorts of innovations “Complex Adaptive Systems”. When Holland chose the word “complex” he was making an important distinction. Complicated mechanisms can be designed, predicted and controlled. Jet engines, artificial hearts or your calculator are complicated in this sense. They may contain billions of interacting parts, but they can be laid out and repeatedly, predictably made and used. They don’t change. Complex systems, by contrast, can’t be so precisely engineered or guessed at with much real certainty. They are hard to fully control. Human immunology is complex, in this sense. The World Wide Web is complex. A rainforest is complex: It is made up of uncountable buzzing, connecting bugs and birds and trees.1!2 Order, to the extent it exists in the Amazon basin, emerges moment-by-moment from countless, constant interactions. The uneven symphonic sound of L’heure Blue, that romantic stopping point at dawn when the night retreats bug by bug and you can hear the forest wakeing bird by bird is the sound of complexity engaging in a never-the-same-twice phase transition. The word “complex” comes to us from the Latin world plex, which nods a