In his new book, Last Harvest: How a Cornfield Became New Daleville, Witold Rybczynski follows the design, construction, and marketing of a new residential subdivision over the course of several years. In the process, he explains how modern homes and communities are built. In today's excerpt, the first of three, Rybczynski examines why we live in houses. Tomorrow's excerpt explains how Americans fell in and out of love with the ranch house. Wednesday's slide show follows the evolution of New Daleville step-by-step, from cornfield to subdivision.