A meaningful book often surpasses its corpus. The recent study by Christophe Jaccoud and Vincent Kaufmann does not escape this rule: if it does constitute “a synthesis of the principal contributions of Michel Bassand to sociology, researches on peripheral regions to those decrypting the multiple faces of metropolisation, going through more conceptual works on mobility or more descriptive works such as the definition of agglomerations”, it does also bring answers to questions, which have to do with the sociology of sociology (how to become a sociologist?), the sociology of science and, above all, the epistemology of social sciences (what is a good explanation in sociology?). [read]