_1550, April._ _A Bull of Julius III_ revokes all dispensations at that time outstanding for the use of heretical books, on the ground that the privilege had been abused and had worked evil.[147] Bulls of similar purport were issued by Paul IV in 1558, in connection with the publication of his Index; by Pius IV in 1564 in connection with the Index of Trent; by Paul V in 1612; by Gregory XV in 1623; by Urban VIII in 1627.[148] It is not surprising that with these difficulties placed in their way, the scholars of the Church found themselves not infrequently at a serious disadvantage in carrying on their controversies with its heretical opponents. As an example of a number of similar utterances may be cited the complaint of Girolamo Muzio, who had been actively engaged in suppressing heresy in Northern Italy. He writes in November, 1550, to the commissary-general of the Inquisition that his work was seriously hampered for want of the privilege of examining the texts of the heresies he was refuting. In March, 1551, the dispensation, for which he had made various applications, was finally granted. _1551, June._ _A Brief of Julius III_ grants permission to the cardinals named as presidents of the Council of Trent to read the works condemned as heretical, and through personal converse with Protestants, to secure the fullest possible acquaintance with the grounds of their heresies. _1561, March._ _A Brief of Pius IV_ gives to the legates at Trent a dispensation identical with that given by Julius III.[149] The letter to the individual legate specifies that the permission to examine heretical literature is granted on the ground of the Pope’s confidence in the strength of his piety and faith and in the trustworthiness of his scholarship. Similar dispensations were given to the Spanish delegates at Trent by the King of Spain. _In 1568_, _Pius V_ sends Cardinal Comendon, with two bishops, to Germany to oppose the spread of Lutheran doctrines. They were charged to purify the German dioceses from heretical books, “which are perpetual instructors and solicit without intermission.” They were instructed further to engage learned men to write against the heretics and to print these orthodox and devout arguments in small books, which being sold at a low price or distributed without charge, should come into the hands of all. Pius promised to provide the funds required for this “missionary” publishing. This method of influencing the public had evidently been suggested by the enormous success of the Protestant presses of Wittenberg. _1587._ _Sixtus V_ issues a Bull for the regulation of libraries in which is restated the penalty of the excommunication _latae sententiae_. _1591._ _Clement VIII_ (in the _Instructio_ of his Index) authorises the bishop to grant such dispensations to trustworthy and faithful scholars, but for no periods exceeding three years. 2. Censorship Regulations in Bavaria, 1561–1582.