This work aims at improving the understanding of en preposition identity within the verbal complementation framework. We come in the continuity of the theoretical approach of Saussure and Harris, for whom language is an autonomous system whose semantic structure can’t be defined through referential or conceptual intuition. We studied the structures N1 V en N2 and N0 V N1 en N2 through a large corpus, thanks to a software facilitating the sorting and classifying of the data. Syntactic tests allowed to list verbs admitting the prepositional group en N as a complement, and to classify them into three groups : those that establish N0 identity (Ses adieux consistèrent en trois baisers, La cylindrée s’exprime en centimètres cubes), those that suppose N0 (L’infirmière sembla gagner en absurde) or N1 (Lucienne me fournissait en chansons) modification and those that assume N0 or N1 transformation (La personne s’évanouirait en chimère). The property of the en preposition is to present en N as constituting and defining for the subject (or object) during the statement.