In this article the thesis of J.M. Léonard defended at the Theological Faculty in Montpellier in 1990 is discussed: Enquête sur l’émergence du hifil en Hébreu Biblique. The author describes the relation of this study to the well-known book of Jenni on the piel. But the main accent of this article is on the methodological side of this thesis: the question in which way the methods and the approaches to the problems involved are of interest for further study on the functioning of the Hebrew stems.