In a sense we approached the world in this book following the spirit of Christo and Jean-Claude. To look at the networks behind such complex systems as the cell or the society, we concealed all the details. By seeing nodes and links, we were privileged to observe the architecture of complexity. By distancing ourselves from the particulars, we glimpsed the universal organizing principles behind these complex systems. Concealment revealed the fundamental laws that govern the evolution of the weblike world around us and helped us understand how this tangled architecture affects everything from democracy to curing cancer.

Where do we go from here? The answer is simple. We must remove the wrapping. The goal before us is to understand complexity. To achieve that, we must move beyond structure and topology and start focusing on the dynamics that take place along the links. Networks are only the skeleton of complexity, the highways for the various processes that make our world hum. To describe society we must dress the links of the social network with actual dynamical interactions between people. To understand life we must start looking at the reaction dynamics along the links of the metabolic network. To undestand the Internet, we must add traffic to its entangled links. To understand the disappearance of some species in an ecosystem, we have to acknowledge that some prey are easier to catch than others.

In the twentieth century we went as far as we could to uncover and describe the components of complex systems. Our quest to understand nature has hit a glass ceiling because we do not yet know how to fit the pieces together. The complex issues with which we are faced, in fields from communication systems to cell biology, demand a brand new framework. Embarking on the journey ahead without a map would be hopeless. Fortunately the ongoing network revolution has already provided many of the key maps. Though there are still many “dragons” ahead, the shape of a new world has become discernible, continent by continent. Most important, we have learned the laws of web cartography, allowing us to draw new maps whenever we are faced with new systems. Now we must follow these maps to complete the journey, fitting the pieces to one another, node by node and link by link, and capturing their dynamic interplay. We have ninety-eight years to suceed at this, and make the twenty-first the century of complexity.