Pope Leo changed the Tridentine rules “without altering their nature.” It is, indeed, difficult to see how the nature of these regulations could have been changed. They simply express the point of view from which the Church must look upon objectionable publications. While opposing and condemning spoken error, the Church surely cannot allow full sway to the printed. In regard to the second part, or Index proper, many wrong notions are current. One of these is, that this Index contains _all_ the books forbidden by the Church, and that there are no others which we are obliged to avoid. From the foregoing remarks, it must, on the contrary, be concluded that there are many other books forbidden by the laws of the Church. The worst of them are not in this special Index at all, because they fall under the general decrees. It is by no means the intention of the Roman authorities to catalogue all the literary virus that has been vomited forth by printing presses all over the world in the course of four and a half centuries. By means of the general laws laid down in the “Officiorum ac munerum” we are in all cases able to see our duty. There are especially two purposes for which books are prohibited separately and by name. Whenever there is a doubt about the nature of a book, recourse may be had to Rome; sometimes the Roman authorities appointed for this purpose, will take up the matter without being appealed to. They will investigate and decide by putting the book on the Index, or, by dismissing it. This is the case with most books publicly censured. It was the case with the books of Schell and Loisy, which, it was strongly urged by learned men, propagated ideas contrary, or at least dangerous, to the faith, though a host of followers admired them as orthodox masterpieces. Rome had to speak, and settled the controversy by condemning the books in question. Dismissal does not always mean that a book is unobjectionable. The authorities may refrain from pronouncing deserved condemnation for reasons of prudence and expediency. Sometimes the preservation of discipline or religious unity necessitates this step. Thus about two hundred years ago the Pope had imposed silence on two factions that were carrying on a theological feud. This silence was violated on both sides, a book appearing for the defence of either position. What was more natural than that both books should be put on the Index? These and similar cases could not be covered so clearly by the general decrees.