In the meantime, the Supreme Council of the Inquisition proceeded with this work with a firm and consistent step. By successive decrees issued between 1521 and 1553, it was ordained that all persons who had in their possession books infected with the doctrines of Luther, and all persons also who failed to denounce the holders of such books, should be excommunicated and subject to severe punishments. These decrees gave to the Inquisition the right to inquire into the contents and the character of whatever books were sold and printed. They also relegated to itself the power to determine what books might be sent to the press. This assumption was made gradually and with little noise, but effectually. While at first there was no direct authority for such action from either the pope or the Kingdom of Spain, it necessarily implied the assent of both, and was carried into effect by means furnished by one or the other. In certain works printed before 1550, the Inquisition began quietly and without any formal authority to take cognisance and control of books that were about to be printed. A curious treatise on exchange, by de Villalon, entitled _Tratado de Cambios_, was printed at Valladolid in 1541. The title-page declared that the book had been “_Visto por los señores Inquisidores_.” In the _Silva de Varia Leccion_, of Pero, printed at Seville, in 1543, the title gives the imperial license for printing, while the colophon adds that of the Apostolical inquisitor. The author was evidently anxious to secure, in addition to a permission resting on law, one which rested on the still more formidable authority of the Church. A system which should effectually preserve the faithful from the contamination of evil by keeping from them the knowledge of its existence comprised two functions; the first was the examination of all books prior to publication, permitting only the innocent to be printed; the second was the scrutiny of the books that had come from the press and the condemnation or expurgation of those containing errors which had escaped the vigilance of the first examiners. Under the rigid institution of censorship in Spain, the first of these duties was assumed by the State and the second was confided to the Inquisition. The first law in regard to Spanish censorship was enacted in 1502 and forbade the printing or importation of any book without an examination and license. The chancellor Gattinara, writing in 1527 to Erasmus, says that in Spain no book could see the light without a careful preliminary inspection which was rigidly enforced. This statement is confirmed in 1540 by Hugo de Celso. The Inquisition had no legal status in the matter of preliminary licensing, but its growing influence caused its judgment to be frequently appealed to in advance. Ticknor makes reference to books of 1536, 1541, and 1546 as bearing records of examination by the Inquisition.