As the object of these measures was to safeguard the faithful against imminent danger, we can easily understand that catalogues of forbidden books were most numerous in those countries that were most exposed to heresy, namely, Germany, Belgium, France, and Northern Italy. It is remarkable that Henry VIII of England, who afterwards fell away from the Church, was among the first to legislate against heretical books, his index of forbidden books appearing as early as 1526. After his apostasy he continued with increased severity the policy of prohibiting books which he deemed objectionable. 4. The Roman Index. More than thirty years after the first index of Henry VIII had appeared, the first Roman Index of Forbidden Books was compiled and issued by order of Paul IV. It remained in force only a few years, till 1564, when the so-called Tridentine Index was published under Pius IV. It was called “Tridentine,” because it had been drawn up by a commission appointed for this purpose by the Council of Trent. It was milder than the Index of Paul IV, and contained divers “Index rules,” the forerunners of the general decrees embodied in the Constitution “Officiorum ac munerum.” The Tridentine Index remained _the_ Roman Index for more than three hundred years. Its “rules” were occasionally modified, new regulations were added or old ones abrogated, other books were inserted in the catalogue; but the essential features remained the same. In 1897, Leo XIII took the matter up again. The index of forbidden books was thoroughly revised. About a thousand were dropped. The “rules,” too, were overhauled, “to make them milder, without altering their nature, so that it cannot be difficult or irksome for any person of good will to obey them.” This, then, represents the whole book legislation of the Church. There are no other documents, except the decrees by which, as occasion demanded, individual books were forbidden. The encyclical of Pius X on Modernism merely enjoins on the bishops special vigilance in regard to publications infected with modernistic views. This universal legislation, however, does not preclude the local prohibition of books by bishops or other ecclesiastical authorities. Thus Spain had, until 1820, its own Index, controlled by the Spanish Inquisition. 5. Books Forbidden by General or Particular Decrees. As we have already mentioned, the Constitution “Officiorum ac munerum” establishes the general laws by which books are forbidden. As will be seen in our Summary, these laws deal with classes of books. The only one named expressly is the Bible. But all the books clearly contained in these classes are as strictly, and sometimes even more strictly, condemned than those listed singly in the second part of the Index.