An instance of a book the censorship of which caused no little difficulty to the authorities of the Index is afforded by the _Decameron_ of Boccaccio. The book had, under the instructions of Paul IV, been placed upon the Index of 1559, and the prohibition was confirmed in that of 1564. In response to an urgent requirement from the public, an expurgated edition was printed for the needs of the faithful by the Giunti in Florence in 1573, under a special privilege from the Duke of Tuscany and from Gregory XIII, who himself contributed a prefatory word. The volume includes further an authorisation from Manrique, Grand Inquisitor, and one from de Pise, Inquisitor-General of Florence. The introduction states that the work has been purged of its obnoxious passages. It appears, however, that the eliminations were confined almost exclusively to the passages which were tainted with heresy, and to the uncomplimentary references to the clergy and to monastic institutions. The amorous incidents are left untouched, but in all cases in which a monk or a cleric, an abbess or a nun is made by Boccaccio to play an undignified or unworthy rôle, the character is replaced by a citizen, a nobleman, or a bourgeoise. The edition of the _Decameron_, revised under the instructions of Gregory XIII, did not prove satisfactory to Sixtus V, and the book was therefore replaced on the Index. The demand for copies on the part of readers, ecclesiastics and others, who were prepared to respect the prohibition of the Index, continued urgent, and the Pope authorised the production of a further expurgated edition, which was printed in Florence in 1582 and reprinted in Venice in 1588. The task of expurgation had been confided to two laymen, Salviati, known as a linguist, and Groto, a poet. This further revision still failed to satisfy the Pope and the book remained on the Index, but it continued in general reading, and the authorities appear finally to have decided to close their eyes to this particular instance of disobedience. The record presents a curious example of a book the vitality of which, persisting through the centuries, defied all efforts for its suppression. It is referred to by the historians as the first _chef d’oeuvre_ in prose that had as yet been produced in Italy, whose literature was so rich in great poems. [Sidenote: Papal Authorisation]