The motor of change in Wilhelmine Germany was the transformation of the material circumstances in which Germans lived and labored. This section presents dramatic evidence of this transformation. Germany's population exploded in the course of a generation, and most of the growth was concentrated in urban areas (Docs. 1, 2, 3). Dramatic increases in agricultural production made both demographic growth and redistribution possible (Docs. 4, 5, 6). By 1913, less than a third of Germany's population was engaged primarily in farming, while the rest was occupied in the secondary and tertiary sectors that were defined respectively by industry and service. The growth of cities was at once a condition and a result of the country's prodigious industrial expansion, which came in the wake of groundbreaking technological advances in steel and chemical processing (Docs. 7, 8, 9, 10). In these core areas of production, which were associated with the "second" industrial revolution, much of German industry was concentrated in capital and labor, as Germany supplanted Great Britain as Europe's foremost industrial power. By the end of the nineteenth century, the products of German industrial enterprise included conveniences – from automobiles and small, electric-powered machinery to aspirin – that have become standard features of modern life (Docs. 11, 12, 13).