A historical perspective is presented by Jean-Claude Chevalier who studies the origin and the development of the concept « auxiliary ». The interpretation of verbal morphology in French, within a Latin frame, encourages the first French grammarians to try and understand the reasons for replacing Latin forms such as amavi or amor by French periphrases. The first step would be to list all the forms called « notae » . The second step would be to restrain them to forms of être and avoir named « auxiliaries ». A third step discovers in the use of the two main auxiliaries a very productive range of significations (Ramus). Henceforth, the category « auxiliary » tends to be incorporated in the verbal analysis (Maupas, Oudin, Vaugelas). Nevertheless, it is only with the Grammaire Générale de Port Royal that a complete analysis is suggested.