This book was in the making for years. At least since the time the Author, in 1951, was working at the University of Chicago to make his personal «somnium Scipionis», that is the positive cross-fertilization between the European tradition of social philosophy and the American empirical research techniques, come true, especially through the collection of life-histories in an interpersonal relation between researcher and research «objects». In this sense, fieldwork does not have a merely ancillary function vis-à-vis theory. It can open new vistas, and offer new insights. Theory and fieldwork are on the same footing as regards the understanding of social phenomena. They need each other.