The popes have at all times exercised the prerogative of their supreme office as guardians of the faith by condemning books opposed to the faith. The latest of such condemnations is that, in 1862, of the works of the Munich professor, Frohschammer, who answered this condemnation by falling away from the Church. There are in all 144 books that were individually proscribed by a papal document. In Pope Leo’s edition they are marked with a dagger. Yet only in cases of the utmost importance did the popes act themselves. To facilitate the government of the world-wide Church, in the course of centuries special committees of cardinals were appointed, to whom part of the pontiff’s various duties were entrusted. These committees are styled Congregations. A larger or smaller number of learned priests and bishops, generally called Consultors, assist the cardinals and practically do the greater part of the work, though the final decision in all cases is reserved to the cardinals. The highest of these Roman Congregations is the _Sacrum Officium_ or “General Inquisition,” called also the “Congregation of the Holy Office,” of which the Pope himself is Prefect. Its purpose is especially to watch over the purity of faith. It is this august body that, after the Pope himself, is in the first place called to judge the doctrines propounded in any book. It was this Congregation that performed the preparatory work for the first Index of Paul IV, and, although another congregation for the examining of books was soon after established, the _Sacrum Officium_ continued to exercise the same power. As may be expected, especially such works as seemed to affect the integrity of the faith, were submitted to this supreme court. In our days the works of the French priest Loisy were proscribed by the _Sacrum Officium_. But the bulk of this work is at present performed by the _Congregatio Indicis librorum prohibitorum_, or “Congregation of the Index of Forbidden Books.” It was founded by Saint Pius V in 1571, seven years after the publication of the Tridentine Index. Since then about eighty per cent. of all individual prohibitions of books have emanated from it. Its Prefect is a cardinal. The present one is Cardinal Segna. The perpetual assistant and secretary are always members of the Dominican order. Besides the seven or ten cardinals there are about thirty consultors, many of whom are bishops. Though three or four prohibitions of books have emanated from other Roman authorities, the practice has been to let either the _Sacrum Officium_ or the Congregation of the Index decide in all cases. The latter Congregation, moreover, had to register all condemnations pronounced by any of the legitimate authorities and to see that they were entered in the new editions of the Index.