Henricus Hovius printed in Liège, in 1569, an edition of the Index of Trent in which (without any reference or specification) certain additional names and titles have been inserted in the alphabetical lists. The title-page states that the Index has been prepared under the authority of King Philip, and in accordance with a decree of the Duke of Alva. The new titles, probably added at the instance of the divines of Louvain, are for the most part repeated in the Antwerp Index of 1570. Reusch points out that this Liège Index is very carelessly printed and is full of errors. The prohibitions of the Trent Index were confirmed under the authority of the diocesan synods of the Spanish Netherlands. One of the diocesan edicts required the printers and booksellers each year to take an oath of fidelity to the faith of the Church, in default of which the license to print was to be forfeited. In 1589, the Synod of Tournai prohibited the booksellers from possessing a copy of the _Index librorum haereticorum_, a catalogue printed yearly for the use of the Frankfort Book-Fair, which was based upon the lists of the Index of Trent, but the titles in which were from year to year brought down to date. The book-dealers were already beginning to realise the value for their business of the labour expended by the Church in the preparation of bibliographies of the books which were most likely to prove of interest to the active minded people of the world. This Frankfort catalogue of heretical books was the beginning of a series of such catalogues in which the work of the Congregation of the Index and of the Inquisition was taken advantage of (with material improvements in the accuracy of the bibliography) to emphasise the value and to further the circulation of the books which had been condemned by the Church. The edict of the bishops who met at Tournai in 1589 appears to have been the first expression of doubt on the part of ecclesiastical authorities as to the effectiveness of the condemnations of the Index in lessening the circulation and the influence of heretical literature.