This book is the outcome of a doctoral thesis presented in February 2006 at the Institut Orientaliste of the Universite Catholique of Louvain. This work investigates the finite verbal forms of ancient Hebrew and the logic of their use as is attested in the Hebrew Bible. After some reflections on the problems and the methodological issues involved, as well as on the value of the Masoretic text as a witness to the ancient Hebrew language (pp. 7-22), the book presents a critical sketch of the theories advanced until now and shows that most of these are built on the traditional quadripartite system (qatal, yiqtol, weqatalti and wayyiqtol) and involve too many exceptions to the rules (pp. 23-200). The second part of the book ends with the main problems of these theories and shows their inadequacy. The third and main part of the book (pp. 201-375) challenges the starting point of much contemporary research by adopting a tripartite system (qatal, long yiqtol and short yiqtol) based on a somewhat different approach than some masoretic elements and on the comparative grammar of the Semitic languages. This tripartite system leads to a description of the Hebrew verbal system which is much more adequate than the quadripartite system.