Book excerpt: First published in French in 1974, David D. Bien's essay on the nature of nobility in old regime France pivoted around the 1781 "Ségur regulation" that required four generations of nobility for most officers entering the army. Once seen as a classic manifestation of the so-called "aristocratic reaction" against commoners, the loi Ségur, in Bien's deft analysis, instead emerges as a telling sign of tensions within an increasingly divided nobility. While exploding crude myths about class conflict and its causative role in the Revolution, Bien mounts a strong case for viewing eighteenth-century social tensions as the product of professional identity as much as social class. This study is presented here for the first time in English with a short preface by Rafe Blaufarb, and a wide-ranging introduction by Jay M. Smith that places Bien's work in the wider context of historical thinking over the past half-century on the origins of the French Revolution.