This article proposes a reading of Michel de Certeau's "The Writing of History" which derives an understanding of the concept of practice as authoritative to the establishment and development of Enlightenment rationality. It is seen as a new form of legitimation established in the redeployment of religious "formalities" in early modernity, supportive of the ostensible deliverance of the projects of reason.Subversive of its moral and ideological operations and geneses, this is an understanding of practice whose subject is the state. Practice, as de Certeau advances it, led to the development of a concept of education productive of a regulatory ambit of social utility, and the student as both a figure of the utile and its moral postulate.This article thematizes the authoritative formality of the concept of practice in its hegemonic origins from early modernity to the thought of Karl Marx. It provides a needed supplement to Marx's still provocative contribution to a persistent counternarrative (of practice as stark corrective to the ineffectual interpretive vagaries of "theory"), one which elides,and thus reinforces, significant prior,and no less persistent, functions of the concept of practice as here elaborated from de Certeau's "The Writing of History."