Knowledge of the history of canon law is of great importance for understanding and practising canon law today. This is true for Roman Catholic canon law, and even more so for Anglican canon law, which lacks a comprehensive codex. The science of the history of canon law comprises several parts: the history of the sources, the history of the literature, and – more recently – the history of the practice of ecclesiastical courts. Professor Erdő, otherwise Archbishop Primate of Hungary and a Cardinal, has now added to his History of the Sources of Canon Law ( reviewed in 8 Ecc LJ 224) a comprehensive description of the development of canon law literature and of the institutions of canon law teaching.

With regard to the different periods of history, the author, not surprisingly, follows in general (though with some amendments) the principles already established in his former book on the sources. The first period (from the beginnings to 1140) is subdivided into the Patristic and Carolingian periods and the period of imperial and Gregorian reform. The second period begins with Gratian and extends to the promulgation of the Liber Extra (1234). The following time, from 1234 to the Council of Trent (1563), the author regards as one, because in its course the Liber Extra was neither superseded nor substantially changed (p 83). However, he prefers to divide it into two periods, their division marked by the year 1348; up to this time the science of canon law flourished, but then a period of decline (‘post-classical’) followed (p 101). The period of Tridentine church law (extending from 1563 to 1917 in the former book) is also now divided in two, by the French Revolution; this is justified by the widespread collapse of the science of canon law in the wake of this Revolution, which was followed by a new upgrowth in the course of the second half of the nineteenth century. In the final period, which began with the promulgation of the (first) CIC in 1917, the science of Roman Catholic canon law has undergone a fundamental change, because it now has to explain and interpret codified law. The sciences of positive canon law and of its history have definitively separated.

The author describes, precisely, the development of the science of canon law; from the mere compilation of sources in the beginning; via the development of a theory of interpretation, destined to bring forth a concordance of discordant regulations, especially important owing to the unsystematic character of canon law in the early period; and the beginning of the explanation of individual regulations; to systematic treatises towards the end of the third period (1234–1348). He gives an overview of the places of canon law study, the ‘schools’ of canon law and the different kinds of canon law literature which are to be found in each period.

Erdő's book is itself a witness to recent developments in the science of canon law. The Latin language of its first edition of 1990 was substituted with Italian in the second, of 1999. So the book marks the end of Latin as the language of science and teaching, even at the canon law faculty of the Pontifical Gregorian University in Rome, for which the book was originally written (cf p 11). One may regret that Anglican canon law, which for a long time continued the law of the pre-Reformation Church as far as it was not inconsistent with ‘Reformation principles’ or – in England – the royal supremacy, is not mentioned at all. In an age of ecumenical endeavours for a rapprochement of separated ecclesial traditions, Norman Doe's magisterial study, The Legal Framework of the Church of England, especially, deserved the author's attention, since it describes the law of the Church of England alongside that of the Roman Catholic Church and so provides a new sort of canon law study ‘in a comparative context’. One can only hope that another edition will include this important aspect of canon law in the latest period of the science.

However, regardless of this desideratum, Erdő's treatise offers invaluable help to anyone who wishes to study the history of the science of canon law thoroughly. It should be translated into the English language, preferably combined with the author's book on the history of the sources, together with which it would form what in earlier times was often published as a ‘history of the sources and literature of canon law’ (eg F Maassen, JF von Schulte).