During the last quarter of the twentieth century, great progress was made in explaining physical, biological, and human social processes that, in former times, were thought to be too complex to be explained in terms of mathematical models. This discussion is concerned with these developments in economics. As a prelude, the basic properties of complex dynamics that have so far been shown to have a significant bearing on economic processes are outlined. Then two applied studies are summarized: one representing macroeconomic development over many centuries, one representing microeconomic development within a decade or generation. These studies imply that economies evolve far from equilibrium.