In four periods : From the foundation of the Church to the Decretum Gratiani , from the Gregorian Reform to the Council of Trent, from Trent to the Codex Iuris Canonici , and from its promulgation in 1917 to the new Codex of 1983, Van de Wiel offers a clear description of the general concepts and constitutive sources of Canon Law. His work is a contribution to the history of canon law and will be of great service both to students and jurists. Constant Van de Wiel is currently professor of Canon Law at the Catholic University of Leuven, Louvain (Belgium), Chancellor and Keeper of the Archives of the Archdiocese of Mechlin-Brussels. He published on the subject in the Louvain Journal of Theological and Canonical Studies : Ephemerides Theologicae Lovanienses , and in several specialized journals.