The establishment of a centre or headquarters for the book-trade of Europe was, of course, of immediate advantage in furthering the knowledge and the distribution of the literature that came into print, and particularly of the books published in Latin. Latin was generally accepted throughout the world as the language not only of scholarship, but of literature, and it was therefore selected by the publishers of the time for the larger portion of the books brought into print. It is true that the work of the early printers of Germany was, unlike that of France and the Netherlands, carried on not in university centres, but, very largely at least, in commercial towns. The lists of these German printers contain a much larger number of books addressed to the general or unscholarly public than was the case with those of their competitors in Paris, Venice, or Leyden, but in Germany also the production of works printed in Latin, for the trade of the world, became each year of increasing importance. For the operations of the general censorship of the Church, the organisation of the book-trade presented certain advantages or at least conveniences. The compilers of the earlier Roman Indexes utilised the bulletins and catalogues of the Book-Fair in securing for their lists information concerning new and forthcoming books of heretical writers or on controversial subjects. As is mentioned in the separate record of certain Indexes, the censors were not infrequently prepared to condemn a book without any examination whatever, simply on the repute of its author, or even on that of its publisher. It occasionally happened, as a result of this method, that a work was prohibited which never came into existence, some obstacle having prevented its completion or its publication after the title had been announced. The first instances of books issued with _Imprimaturs_ are two printed at Cologne in 1479 and sanctioned by the university, and a third printed at Heidelberg in 1480, under the authorisation of the Patriarch of Venice. The earliest mandate of which there is record for the appointment of a censor of books was issued in 1486 by Berthold, Archbishop of Mayence. The Archbishop forbids the translation into the vernacular of any books from Latin, Greek, or other languages, or the sale of translations brought in from without, until these have been examined and approved by censors appointed for the purpose from the university of Erfurt.[143] He instructs the Burgomaster of Frankfort to make examination of all books at the Frankfort Fair before the permit should be given for their sale. In 1524, the Archbishop of Mayence claims, on the double ground of his position as High Chancellor of the empire and as a representative of the authority of Rome, the right to supervise the book-trade of the empire, and he makes immediate application of this authority to the control of the sale of books at the Frankfort Fair. [Sidenote: Frankfort]