The Catholic Index of Forbidden Books: A Brief History

Banned and Challenged Books, Censorship, Religion

By: Robert Sarwark

To respond to the above-mentioned questions, this Sacred Congregation for the Doctrine of the Faith, after having asked the Holy Father, announces that the Index remains morally binding, in light of the demands of natural law, in so far as it admonishes the conscience of Christians to be on guard for those writings that can endanger faith and morals. But, at the same time, it no longer has the force of ecclesiastical law with the attached censure.

— “Notification regarding the abolition of the Index of books,” June 14, 1966

When I was an MLIS student at the University of Illinois, I had the great honor of studying with professor Emily Knox, a respected author and expert on issues relating to intellectual freedom, censorship, and book banning. Though the first course I took under Dr. Knox did not specifically focus on these issues, throughout the semester I learned more about her work and publications and became fascinated with the prevalence of censorship throughout the world’s history and into the present moment. With all this in mind, when it came time to write my final paper for the course, I had zeroed in on my topic: The Catholic Church’s Index Librorum Prohibitorum, the Index of Forbidden Books that existed from around 1600 all the way until 1966.

I can’t (and shouldn’t) get into the details of so many centuries in this post — for that, feel free to check out the site I created, Bibliography of the Damned. But a brief history of the Index and its many implications will hopefully suffice here.

Index des livres interdits [Index of Prohibited Books], Vol. XI (1600-1966), Edited by J.M. de Bujanda, with Marcella Richter, 2002The Index Librorum Prohibitorum was a list of books banned for lay Roman Catholic readership. Officially — though the Church was never fully explicit in its means of prosecution of such rules — any individual who dared read any books included on this list risked excommunication and, thus, spiritual damnation. As mentioned above, the Index was definitively compiled Church-wide starting around 1600 and semi-regularly published in Latin (and, later, in translation) by the Vatican starting in 1632.

The process of deciding which books were to be included was regulated in accordance with various canons (religious laws) regulating the Church’s official policies on printed literature. Before they were consolidated into one master serial publication, various subsets of the Church such as the Universities of Paris and Louvain and the Spanish and Portuguese Inquisitions had independently published their own indices of forbidden books throughout the sixteenth century. Finally, after almost 400 years, as a result of the reforms promulgated by the Second Vatican Council (1962-1965), the Index and its official mechanisms were officially decommissioned in 1966.

Some notable authors on the Index include novelist Gustave Flaubert (Madame Bovary), historian Edward Gibbon (The History of the Decline and Fall of the Roman Empire), political intriguer and legendary lothario Casanova (his memoirs), and revolutionary astronomer Galileo (Dialogue on the Great World Systems was banned in 1634 and then removed from the Index in 1822). In addition, there are many hundreds of more obscure listings on the Index. All of the Index’s editions over the centuries were cumulatively compiled and published in 2002 by Renaissance and Catholic censorship scholar J.M. de Bujanda.

The prevalence of such a large number of prolific, “household-name” thinkers and writers on this list totaling 3,000-plus authors and 5,000-plus individual titles speaks to the world-altering effects that one particular technology had during the Renaissance era: the printing press. This new machine’s capability of quickly transmitting new and potentially revolutionary ideas cannot be understated; once widespread, it posed an existential threat to the Catholic Church’s ideological and political authority over most of Europe and beyond, powers that by 1600 had been expanded and maintained for over a millennium.

As any bibliophile worth their salt knows, Johann Gutenberg invented the movable-type printing press around 1450, allowing for, soon afterwards, the mass dissemination of books, pamphlets, broadsides (posters), and other printed materials. Without the printing press, for example, the “99 Theses” of Martin Luther (1517) would have to have been copied out by hand, a process that takes exponentially longer to complete than the labors of a well-staffed print shop.

Simply put, neither Lutheranism nor Protestant Christianity in general may have ever spread without the printing press. As Protestantism took hold in countries such as the Netherlands and England by the 16th and 17th centuries, independent printers and publishing houses did as well. Much to the Vatican’s chagrin, published works were no longer under the control of the Catholic Church and its monasteries full of quill-pen-wielding scribes and copyists. By about 1500, the dam of information and documentation of all kinds, which we nowadays take for granted, had just begun to spring its first major leaks.

The Index continues to pique my interest, even three years after writing my paper on it, for various reasons. But probably the most prominent is that it provides, somewhat ironically, an excellently well-documented registry of notable and/or notorious writings throughout the centuries since the printing press was invented. It offers a guide, as hopefully my site shows, to what caught the Vatican authorities’ attention as scandalous, unorthodox, morally repugnant, or otherwise anathema to its teachings. And though it does present a bit of an awkward case considering it was only discontinued in 1966, the underlying spirit of the Index, i.e., religious censorship, remains in some force in a few corners of Catholicism such as film criticism. As one modern Catholic writer defended in 2016, 50 years after the Index was discontinued, “Truths are like axes and hammers, tools that can be turned into weapons. The Church trusts people with the truth, though sometimes it comes with ‘This does not mean that …’ warnings. With errors, it sets off the alarm.” As seen in the quote at the top of this article, this somewhat stern caveat was indeed the intention in 1966.

History and modernity are directly linked through the ways in which we obtain, process, verify, and disseminate information. A massive bibliography such as the Index (almost 1,000 pages in Bujanda’s edition) is an invaluable trove of historical information. It deserves to be studied because it offers such an expansive case of institutional censorship and intellectual freedom, issues that most certainly are still with us today. So during the next Banned Book Week, along with the many modern banned or censored titles at your disposal, consider one listed on the Index, too. There’s no shortage of great literature there.


Robert SarwarkRobert M. Sarwark is a librarian at the Art Institute of Atlanta. He is originally from Chicago and enjoys dogs, pizza, and writing bios in the third person. Find him on Twitter @RobSarwark.


  • Hello,

    Recently I spoke with my mom (age 86) about a pledge she remembered having to take each year, through school and in Church, pledging not to read certain books. I’ve been looking for the wording of that pledge without success. I found plenty about the Legion of Decency, but this seems to be focused on film and my interest is about books specifically. Do you have any leads about what a grade-school nun might tell her students about taking the upcoming pledge?

    Thank you,
    Deirdre Fischer

  • Thanks much for your comment, Deirdre.

    That is fascinating! I haven’t come across it in my research thus far but I will certainly look for that pledge or anything similar going forward. My hunch is that that may have been either a school or parish initiative, depending on who was in charge. But that’s just my hunch.

    Also, if you’d like, I’d be happy to connect directly: I’d be interested in speaking with your mother as well.

    Thank YOU,


  • Out of curiosity, which was the first book ever to be condemned by the Church or to be entered in the Index?

  • Hi! This is an excellent question. It’s a little tricky to answer, however, for a few reasons. (SPOILER: There have been many Indexes!)

    For one, the Church has banned books going back to its earliest foundations during the first centuries after Jesus Christ’s death (c. 30 AD). These banned books included texts considered apocryphal, or non-canonical, especially in regards to the New or Christian Testament, or otherwise sinful, scandalous, profane, etc. etc.. This was not done in a particularly systematic manner, however, as condemnations were fleeting and depended on the Church’s leadership at the given time.

    Several semi-autonomous indexes existed in various parts of Europe. The first of them was published by the Faculty of Theology of the University of Paris (La Sorbonne), in 1544.

    The Church did not have a fully consolidated Index until about 1564, upon the conclusion of the Council of Trent. If we take this date as our starting point, it becomes easier to isolate individual titles. Note that this date is not too long after Martin Luther initiated the Protestant Reformation in 1517. Essentially, any attempt at a definitive system of banning books or other texts is a response to the religio-cultural revolution that Luther set ablaze.

    That said, according to de Bujanda et al. (Eds.), it is fairly easy to pinpoint those books entered into the Catholic Index of Forbidden Books around the year 1564 (day-specific dates of condemnation were not recorded — or at least are no longer extant — until 1571, when the Vatican’s Congregation of the Index was established).

    A short selection of these books is as follows:

    –A commentary on a work by the Roman historian Tacitus: ALTHAMER (BRENTZIUS), Andreas (c.1498-1560), Commentaria Germaniae in P. Cornelii Taciti Libellum de situ, moribus et populis Germanorum. Nuremberg: Johann Petreius, 1536;

    –Four texts published in 1557 by Italian humanist and libertine Pietro ARETINO (1492-1556);

    –A treatise on law by SCHURFF (SCHURPF), Hieronymus (1481-1554). Consiliorum, seu Responsorum iuris…, centuria prima. Frankfurt: Christian Egenolff, 1556.

    Hope this answers your question, at least somewhat!

  • In the1950’s I had Catholic friends who referred to the Churches”index by another name. I think it began with the letter “c.” Do you know what that word was?

  • Hi Linda, thanks for reaching out. Maybe the “c” word was congregation, as in “the Congregation of the Index”? Other relevant “c” words that come to mind include “canon,” “code of canon law,” “censorship”. I hope this helps but if not, please check out for more information.

  • Thank you for such an interesting article!

    I was just wondering if you were aware of the extent to which Catholics, especially during 16th-17th centuries, followed the Index(es) in Europe more generally? If the index was difficult to enforce outside of the Roman curia, was it more about spiritual intention rather than the possibility of punishment which ensured Catholics would not read the banned books/indeed how effective was it in encouraging Catholics not to read them?

    Thank you very much!

  • Hi Izzy! Thanks much for reading and for responding. This is a great question.

    The reality is, so many people were illiterate during that time that we should view these bans as primarily political. You are right that actually enforcing them in a real or targeted way was virtually impossible outside of the clergy.

    That said, we can imagine how things may have easily trickled down, from the Vatican, to the elite, to the intelligentsia, to universities (though there were far fewer back then than now), to booksellers, to the (relatively small) reading public, etc., etc.

    So the effectiveness of the Index may have been scattershot, but writ large it most certainly contributed to anti-intellectual tendencies and consolidation of the status quo in majority-Catholic populations. That status quo could only do so much, in the long run however, as the impacts of the printing press + Protestantism + the Enlightenment emerged and spread between the 16th and 20th centuries. By 1966, the Vatican in effect admitted defeat when they finally shut down the whole Index apparatus.

    Hope this helps! Feel free to follow me on Twitter at @bibofthedamned if you’d like to continue the conversation.

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