After the beginning of the Reformation in Germany, the operations of the censorship in Spain were carried on with renewed vigour. Special efforts were naturally made to protect the faithful in Spain from contamination through the importation of heretical books from Germany. A letter of June 25, 1524, written by Martin de Salinas, mentions that a ship from Holland bound for Valencia had been captured by the French and then recaptured and brought into San Sebastian. In discharging the vessel, there were found two casks of Lutheran books which were publicly burned. Salinas writes, some months later, that three Venetian galleasses had arrived at a port in Granada, bringing large quantities of Lutheran books. The books were burned and the captains and crews arrested. An edict of the Supreme Council of the Inquisition, issued in August, 1530, urged the inquisitors to increased vigilance in connection particularly with the destruction of certain Lutheran writings that had been introduced under false titles or under the names of Catholic authors. The inquisitors were ordered to add to the Edict of Denunciations, published annually, a clause requiring the denunciation of all who possessed such books or of all who had read them.[111] In spite of the watchfulness of the inquisitors and of the customs officials, it is reported that, in 1570, no less than thirty thousand copies of a Spanish version of the _Institutes_ of Calvin were brought over the frontier.[112] It is the conclusion of Ticknor that by the end of the 16th century, bookselling in Spain, in the sense in which the term was used elsewhere in the world, was practically unknown, and the Inquisition and the confessional had often made most rare what was most desirable. In March, 1521, papal briefs were sent to Spain, warning the Spanish Government to prevent the further introduction of books written by Luther and his followers, copies of which had, it was believed, been penetrating into the country for about a year. These papal briefs were addressed to the civil administration, which still, in form at least, retained in its own hands the control of such matters. It was, however, more natural and more in accordance with the ideas then prevalent, not only in Spain but in other countries, to look to the ecclesiastical power for remedies in a matter connected with religion. This was certainly the attitude of the great body of the Spanish people. In less than a month (as is evident from the date of the briefs in question) and possibly even before these briefs were received in Spain, the grand inquisitor addressed an order to the tribunals under his jurisdiction, requiring them to search for, and to seize, all books supposed to contain the doctrines of the new heresy. The measure was bold and proved successful.