Liberality and largesse are regularly presented as very high moral qualities in the old French epics and romances (12th-13th century). The object of this work is to study the question of the king's largesse with the help of anthropology and its researches on the gift as social practice, which has an important politic and symbolic sense. The texts showing the king to be doing largesse describe a sort of enchanted moment : largesse creates an affective and moral relationship between the king, who gives, and his vassals, who receive ; this relationship vanishes the institutional base and the juridical dimension of the royal power ; the king commands without coercion, the vassals serve in a free and voluntary way. The objective truth of this largesse is yet the foundation or the perpetuation of a veritable System of domination, but this objective truth of largesse (largesse obliges and constrains) is denied and driven back. The ideal atmosphere of the texts describing the king's largesse results from a collective self deception about the deep nature of a practice which was very important for the social live and the interpersonal relations into the feudal aristocracy, of whom the king was the first member.