In this he inveighed against the printing of matter prejudicial to healthy doctrine, to good manners, and, above all, to the Catholic Faith or anything that should give scandal to the faithful.

He threatened the printers of impious works with excommunication should they persist, and enlisted secular weapons to punish them in a temporal as well as a spiritual manner.

He ordered the preparation of indexes of all works containing anything hurtful to religion, and pronounced a ban of excommunication against all who should peruse the books so indexed.
Thus Alexander invented the Index Expurgatorius.
There is abundant evidence that he was a fervid celebrant, and of his extreme devotion to the Blessed Virgin--in whose honour he revived the ringing of the Angelus Bell--shall be considered later.
Whatever his private life, it is idle to seek to show that his public career was other than devoted to the upholding of the dignity and honour of the Church..