The processes of nature can make an infinite number of human faces, each one unique, each one beautiful. The same is true for daffodils, streams, and stars. But man-made creations-especially the towns and buildings of the 20th century-have only occasionally been really good, more often mediocre, and in the last 50 years have very often been deadly. What is the reason for the difference?

In Book 2, Alexander explains in detail the kinds of process that are capable of generating living structure. The unfolding of living structure in natural systems is compared to the unfolding of buildings and town plans in traditional society, and then contrasted with present-day building processes.

The comparison reveals deep and shocking problems which pervade the present day planning and construction of buildings. Pervasive changes are needed to create a world in which living process-and hence living structure-are possible; these are changes which are ultimately attainable only through a transformation of society.

It is the use of sequences which makes it possible for each building to become unique, exactly fitted to its context, and harmonious. And it is also this use of sequences which makes it possible for people to participate effectively in the layout of their own buildings and communities.