the present paper intends to outline the feudal conception of dominium, i. e., of power and freedom. In order to do this, the first task is to look into the history of that idea in its different statements. Then several authors appear, from Antiquity to Nineteenth Century: from Tacitus to Guizot, through Gregory of Tours (6th Century), Hotman (16th Century), Audigier or Tarault (17th Century), Boulainvilliers, Freret or Chastellux (18th Century). No renowned medievalist so far, except for Ian Wood, was able to draw attention to the importance of Foucault's 1975-76 course in the College de France, Il faut defender la societe (Society Must be Defended), to make sense of all this. The second task lies in defining the nature of feudal understanding of dominium according to Henri de Boulainvilliers' philosophy of history, a leading figure in the issue. Finally, we sketch a comparison between the feudal conception of dominium and that suitable to the medieval Aristotelianism..