mprised 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]

The effect of the censorship of the press has been variously estimated.
The Index was early dubbed _sica destricta in omnes scriptores_ and
Sarpi called it "the finest secret ever discovered for applying
religion to the purpose of making men idiotic." Milton thundered
against the censorship in England as "the