21. Pius IV (b. 1499, Pope 1559–1565). Index librorum prohibitorum, cum regulis confectis per patres a Tridentina Synodo delectos, auctoritate sanctiss. D.N. Pii IIII, Pont. Max. comprobatus. Rome: Paulus Manutius, 1564.

The first Tridentine Index prohibited the complete writings of 610 authors, identified 69 additional authors whose prohibited works were listed individually, and banned 297 anonymous titles. As would be the case with all indexes of prohibited books, no explanation for a text’s suppression was provided. Owned by an unidentified Spanish nobleman in the later sixteenth century, Bridwell Library’s copy of the first edition is bound with a contemporary handwritten Spanish translation of the collected decrees of sessions 17 through 25 of the Council of Trent.