This book, written by two well-known scientists, represents an excellent ad- dition to the Springer Series in Synergetics in several ways. It shows how by rather simple models we can gain remarkable insights into the behavior of complex systems. At the same time it demonstrates the progress made in this interdisciplinary field. While in the early days of Synergetics, the self- organized coherent action of atoms in the laser - a physical device - was in the foreground of interest (cf. my book Synergetics: An Introduction (Springer, Berlin, Heidelberg, New York 1977)), the coherent action of...