Rare Books Highlights: Books from the Index librorum prohibitorum

This week is Banned Books Week, an annual celebration of the freedom to read. Book banning and censorship have gone on for centuries, and one of the most prominent vehicles for such activity in the Western world was the Index librorum prohibitorum, the list of books banned by the Roman Catholic church for spreading heretical ideas. The Index made its first appearance in 1559 under Pope Paul IV, and it carried broad restrictions, including all books by heretical authors and printers, and books without identifiable authors or printers. The Pauline Index was not readily accepted because of the severity of its restrictions, and so it was replaced in 1564 by the Tridentine Index, coming out of the Council of Trent, the Roman Catholic church’s 19th ecumenical council convened in response to the Protestant Reformation. This Index followed more narrow rules for prohibiting books. For example, books of a non-religious nature by a heretical author were not necessarily prohibited. The Tridentine Index laid the foundation for later editions of the Index. In 1571, the Sacred Congregation of the Index was established to oversee and periodically update the Index and to investigate particular cases of denounced writings. The final 20th edition of the Index appeared in 1948, and it was officially abolished by Pope Paul VI in 1966.

This post highlights two famous astronomy books from our collections that spent time on the Index.

Nicolaus Copernicus. De revolutionibus orbium coelestium. Basileae, Ex Officina Henricpetrina, 1566. Call number: QB41 .C79d

Nicolaus Copernicus. Portrait from Toruń, beginning of the 16th century.

Copernicus overturned the long-held idea of an earth-centered universe in his De revolutionibus. He demonstrated mathematically that the Earth and the other planets revolve around the sun, and that the moon revolves around the Earth, as shown in the diagram below.

Page showing a diagram of the heliocentric solar system model from Copernicus’s De Revolutionibus.

The book was not censored immediately upon publication. Though the work received criticism for being in conflict with Joshua 10:13 from the Bible, in which the Sun is commanded to stand still in the sky, thus indicating that the Sun circles the Earth, it took over 70 years for the book, first published in 1543, to come under consideration by the Congregation of the Index, due in large part to the astronomical work of Galileo (see more below). In 1616, the Congregation placed the work on the Index “until corrected,” and in 1620 ten specific corrections to the text were outlined that were designed to make heliocentricism appear to be theoretical only and not a description of a natural phenomenon.

Some copies of the book were “corrected” by hand, especially copies owned by people living in Roman Catholic countries. The ISU copy is, perhaps unfortunately, not corrected. Check out this blog post from University of Rochester River Campus Libraries for examples of a corrected copy.

Coat of arms stamped in gold leaf on brown leather.

Coat of arms on the cover of ISU’s copy of De Revolutionibus.

Although lacking the corrections, the ISU copy does have some interesting elements. Check out the coat-of-arms on the binding. A note pasted inside the front cover indicates that this coat-of-arms was used by the “eldest son during father’s lifetime” of the Berkeley family, a family from the English nobility from a long-running Saxon line.



Galileo Galilei. Dialogo di Galileo Galilei. Fiorenza i.e. Napoli, 1710. Call number: QB41 .G35 D5x 1710

Justus Sustermans’ Portrait of Galileo, 1636. National Maritime Museum, Greenwich, London.

The writings of Galileo and Copernicus are closely linked in their relation to the Index. In fact, he wrote as early as 1597 to both Johannes Kepler and a former colleague named Jacopo Mazzoni, sharing his support for Copernicus’ model of the solar system. Galileo’s work at this time focused largely on mechanics, but with the invention of the telescope in 1608, he turned his attentions to improving it. In 1610, Galileo took his improved telescope and starting looking to the heavens. Galileo made a number of famous discoveries, including four moons of Jupiter, which he published in a book titled Sidereus nuncius. His made later discoveries, including the phases of Venus, that removed objects to the Copernican system, and in 1613 he published Letters on Sunspots, in which he first spoke openly in favor of the Copernican system. Later than same year, theological objects to the Copernican system were raised, and Galileo rose to its defense. He wrote on the necessary separation between scientific investigation and theological issues, and he even went to Rome in late 1615 to advocate against the suppression of the Copernican system and to clear himself from any condemnation. Galileo failed to stop the 1616 edict against De revolutionibus, and while no actions were taken against him or his works, he was instructed to no longer defend Copernicanism.

In 1623, Pope Urban VIII was appointed in Rome. Galileo met with the new pope in 1624, and over the course of several meetings, the pope granted Galileo permission to write about the Copernican system, so long as he presented it as a theory. The result was Galileo’s Dialogue Concerning the Two Chief World Systems. The book took the form of a conversation between a spokesman for Copernicus, a spokesman for the Ptolemy and Aristotle (who promulgated a geocentric model of the solar system), and an educated layman for whose support the other two are vying. The follower of Ptolemy and Aristotle is named Simplicio, which looks suspiciously like a double entendre for a simple-minded person, since the Italian for simple is semplice. While on the surface Galileo remains uncommitted to the Copernican system, the course of the book systematically disproved the geocentric model of the universe. He also put the arguments used by Pope Urban VIII himself in conversations with Galileo into the mouth of Simplicio, which seems to have caused great personal offense to the pope. Upon publication of the Dialogo in 1632, copies were sent to Rome, and before long Galileo was ordered to appear before the Inquisition.

Galileo’s Dialogo was written as a conversation between three speakers, but it proved many mathematical points, as illustrated by the diagram on the right page.

The results of Galileo’s trial are well-known. He was found guilty of heresy in his support of the Copernican system and was forced to abjure those views. He was sentenced to imprisonment, but due to health issues the sentence was commuted to house arrest for the remainder of his life. Finally, the Dialogo was placed on the Index.

Galileo continued to write while under house arrest, publishing an important work in physics, Discourses and Mathematical Demonstrations Relating to Two New Sciences, in 1638. Because the publication of any of Galileo’s works had been banned, he had to have the manuscript smuggled out and published in Holland by Elzevir.

ISU’s copy of the Dialogo is a large-paper copy of the second vernacular edition, meaning the edition that was printed in Italian, rather than the original Latin. Published in 1710, almost 80 years after the first edition and 68 years after Galileo’s death in 1642, it was still a prohibited work. Perhaps that is why there is no publisher indicated and there is a disguised printing location–the title page says Florence, but bibliographic scholars have identified that it was actually published in Naples. This edition is important in that it contains, in addition to the Dialogue, several other related texts that were not available at the time of the first edition. Notably, it includes the first Italian printing of Galileo’s Letter to the Grand Duchess Christina, in which he argued for the independence of science from religion, and a reprint of Paolo Foscarini’s Lettera, which was the first Italian work defending the Copernican theory. This last work was banned in 1616 at the same time as Copernicus’ De revolutionibus, and existing copies were burned. Also of interest is the Inquisition’s sentence of Galileo and his abjuration.

Both works by Galileo and Copernicus remained on the Index until 1835, when the Catholic Church abandoned its official opposition to heliocentrism.


This post was written with help from:

Dialogue Concerning the Two Chief World Systems.” Wikipedia. 30 August 2017. en.wikipedia.org/wiki/Dialogue_Concerning_the_Two_Chief_World_Systems

De revolutionibus orbium coelestium.” Wikipedia. 9 September 2017. en.wikipedia.org/wiki/De_revolutionibus_orbium_coelestium

Dictionary of Scientific Biography. Charles Coulston Gillispie, ed. Scribner, 1981.

“Galileo Galilei.” Wikipedia. 18 September 2017. en.wikipedia.org/wiki/Galileo_Galilei

Index Librorum Prohibitorum.” Wikipedia. 28 July 2017. en.wikipedia.org/wiki/Index_Librorum_Prohibitorum

“List of authors and works on the Index Librorum Prohibitorum.” Wikipedia. 23 June 2017. en.wikipedia.org/wiki/List_of_authors_and_works_on_the_Index_Librorum_Prohibitorum

“Nicolaus Copernicus.” Wikipedia. 18 September 2017. en.wikipedia.org/wiki/Nicolaus_Copernicus

Two New Sciences.” Wikipedia. 21 September 2017. en.wikipedia.org/wiki/Two_New_Sciences

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s