Partly in imitation of this work of Louvain, partly in consequence of the foundation of the Inquisition, the Roman Index of Prohibited Books was promulgated. Though the bull founding the Roman Inquisition said nothing about books, their censure was included in practice. Under the influence of the Holy Office at Lucca a list of forbidden works was drawn up by the Senate at Lucca, [Sidenote: 1545] including chiefly the tracts of Italian heretics and satires on the church. The fourth session Council of Trent [Sidenote: April 8, 1546] prohibited the printing of all anonymous books whatever and of all others on religion until licensed. A further indication of increasing severity may be found in a bull issued by Julius III [Sidenote: 1550] who complained that authors licensed to read heretical {421} books for the purpose of refuting them were more likely to be seduced by them, and who therefore revoked all licenses given up to that time.
[Sidenote: September, 1557]
When the Roman Inquisition issued a long list of volumes to be burnt publicly, including works of Erasmus, Machiavelli and Poggio, this might be considered the first Roman Index of Prohibited Books; but the first document to bear that name was issued by Paul IV. [Sidenote: 1559] It divided writings into three classes: (1) Authors who had erred ex professo and whose whole works were forbidden; (2) Authors who had erred occasionally and some of whose books only were mentioned; (3) Anonymous books. In addition to these classes 61 printers were named, all works published by whom were banned. The Index strove to be as complete as possible. Its chief though not its only source was the catalogue of Louvain. Many editions and versions of the Bible were listed and the printing of any translation without permission of the Inquisition was prohibited. Particular attention was paid to Erasmus, who was not only put in the first class by name but was signalized as having "all his commentaries, notes, annotations, dialogues, epistles, refutations, translations, books and writings" forbidden.
[Sidenote: Tridentine censorship, February 26, 1562]
The Council of Trent again took up the matter, passing a decree to the effect that inasmuch as heresy had not been cured by the censorship this should be made much stricter, and appointing a commission in order, as, regardless of the parable,[1] it was phrased, to separate the tares from the wheat. The persons appointed for this delicate work comprised four archbishops, nine bishops, two generals of orders and some "minor theologians." After much sweat they brought forth a report on most of the doubtful authors though {422} the most difficult of all, Erasmus, they relinquished to the theological faculties of Louvain and Paris for expurgation.
[Sidenote: 1564]
The results of their labors were published by Paul IV under the name of the Tridentine Index. It was more sweeping, and at the same time more discriminating than the former Index. Erasmus was changed to the second class, only a portion of his works being now condemned. Among the non-ecclesiastical authors banned were Machiavelli, Guicciardini and Boccaccio. It is noteworthy that the Decameron was expurgated not chiefly for its indecency but for its satire of ecclesiastics. Thus, a tale of the seduction of an abbess is rendered acceptable by changing the abbess into a countess; the story of how a priest led a woman astray by impersonating the angel Gabriel is merely changed by making the priest a layman masquerading as a fairy king.
The principles upon which the prohibition of books rested were set forth in ten rules. The most interesting are the following: (1) Books printed before 1515 condemned by popes or council; (2) Versions of the Bible; (3) books of heretics; (4) obscene books; (5) works on witchcraft and necromancy.
In order to keep the Index up to date continual revision was necessary. To insure this Pius V appointed a special Congregation of the Index, which has lasted until the present day. From his time to ours more than forty Indices have been issued. Those of the sixteenth century were concerned mainly with Protestant books, those of later centuries chiefly deal, for the purposes of internal discipline, with books written by Catholics. One of the functions of the Congregation was to expurgate books, taking out the offensive passages. A separate Index expurgatorius, pointing out the passages to be deleted or corrected was {423} published, and this name has sometimes incorrectly been applied to the Index of prohibited books.
[Sidenote: Effect of the censorship]