The trial of Galileo Galilei by the roman inquisition: a comprehensive overview

Journal of Social Sciences Vol. VIII, no. 1 (2025), pp. 169 - 179 Fascicle Social Science ISSN 2587-3490 Topic History eISSN 2587-3504 Journal of Social Sciences March, 2025, Vol. 8 https://doi.org/10.52326/jss.utm.2025.8(1).12 UDC 94:52:34 THE TRIAL OF GALILEO GALILEI BY THE ROMAN INQUISITION: A COMPREHENSIVE OVERVIEW Lino Bianco *, ORCID: 0000-0001-8779-2351 University of Malta, MSD 2080 Msida, Malta * Corresponding author: Lino Bianco, [email protected] Received: 02. 12. 2025 Accepted: 03. 18. 2025 Abstract. One of the most famous trials in world history is that of the Florentine scientist Galileo Galilei in front of the Roman Inquisition. Based on historical sources, this article presents a comprehensive overview of the 1633 trial, the roots of which dated to Galileo’s 1613 publication on sunspots. It culminated with his publication of the Dialogue concerning the two chief world systems, Ptolemaic and Copernican. Although condemned by the Inquisition to imprisonment for an indefinite period, his sentence was commuted to house arrest until death. Keywords: Galileo Galilei, 1633 trial, Copernicus, Bellarmino, Bellarmine, Maculani, Roman Inquisition, heliocentrism. Rezumat. Unul dintre cele mai cunoscute procese din istoria lumii este cel al savantului florentin Galileo Galilei în fața Inchiziției romane. Bazat pe surse istorice, acest articol prezintă o prezentare cuprinzătoare a procesului din 1633, ale cărui rădăcini datează de la publicația lui Galileo din 1613 despre petele solare. Punctul culminant a fost publicarea lui intitulată Dialog privind cele două sisteme principale ale lumii, Ptolematic și Copernican. În ciuda faptului că Inchiziția l-a condamnat la închisoare pe perioadă nedeterminată, pedeapsa a fost comutată în arest la domiciliu până la moartea lui. Cuvinte cheie: Galileo Galilei, procesul 1633, Copernic, Bellarmino, Bellarmin, Maculani, Inchiziția romană, heliocentrism. 1. Introduction Hosted by the University of Missouri–Kansas City, the Famous Trials website, set up in 1995 by Douglas Linder, covers over 50 famous trials in world history. One of them is the trail of Galileo Galilei (1564–1642), who was raised in Florence after his family moved from Pisa when he was young – with respect to which Linder includes a chronology [1]. He traces the beginning of the story to the Polish polymath Nicolaus Copernicus (1473–1543), who put forward the first model of a heliocentric system for the universe in 1514, half a century prior to Galileo’s birth. This proposed system ran contrary to the Ptolemaic model whereby the sun orbits the stationary earth. Linder also refers to the Danish astronomer Tycho Brahe (1546– 1601) who proposed a compromise between the Copernican and Ptolemaic models: the earth as the stationary centre of the universe with the sun and moon orbiting it. Brahe’s model included other planets orbiting the sun. By 1597, Galileo fully embraced the Copernican model of the universe. He wrote to the German astronomer Johannes Kepler (1571–1630) that “Like you, I accepted the 170 L. Bianco Journal of Social Sciences March, 2025, Vol. 8 Copernican position several years ago and discovered from thence the causes of many natural effects which are doubtless inexplicable by the current theories” [2, p. 11]. Three years later, the Italian thinker Giordano Bruno (1548–1600) was convicted of heresy – including his cosmological theories which conceptually extended to the Copernican model – by the Holy Office and burned at the stake in Campo de’ Fiori, Rome. In 1610, Galileo built a ×30 telescope which he used for astronomical observations, including of moons revolving around Jupiter, thus confirming the veracity of the Copernican model. He improved on the design – his own version of the Dutch Perspective Glass – credited to either Hans Lippershey (c. 1570–1619) or Zacharias Janssen (1585–pre-1632), both Dutch master lens grinders and spectacle makers who experimented with lenses to view distant objects. A year later, Kepler explained how a convex objective lens and a convex eyepiece lens could be used to create a much more effective telescope. In 1611, Galileo observed sunspots. In April of the same year, Jesuit Cardinal Roberto Bellarmino (1542–1621) (or Cardinal Robert Bellarmine if in English) – a former rector of the Collegium Romanum which was established in 1551 by St Ignatius of Loyola (1491–1556), 11 years after he founded the Society of Jesus (Jesuits) – asked Jesuit mathematicians to confirm or disprove Galileo’s findings. They replicated Galileo’s observation but did not converge with his interpretation. 2. Materials and method The objective of this article is to impart a concise, comprehensive overview of the trial of Galileo Galilei by the Roman Inquisition. It concludes by outlining the Inquisition’s judgment and execution of the sentence; the former is reproduced in full as an Annex. Significant to all publications to date is I documenti del processo di Galileo Galilei, published by the Pontifical Academy of Sciences in 1984 [3]. Use has been made of Karl von Gebler’s (1850–1878) revised version of Galileo’s trial based on primary sources [4]. The account of his trial is given in several books, notably de Santillana [2] and, more concisely, Drake [5]. Applying the classification proposed by Henry Ansgar Kelly [6], Linder [1] ascribed three phases to Galileo’s brush with the Holy Office: (i) non-trial (1616); (ii) pre-trial (1632– 1633); and (iii) trial (10 May 1633). 3. Galileo and the Roman Inquisition One can trace the non-trail phase to 1613, the year Galileo published his work on sunspots [7] which supported the theory that the sun rotates on an axis. The chronology given by Linder which address this phase is given in Table 1. Table 1 Chronology: non-trial phase (After [1]) Date Event November 1613 Lorini launches the first attack from the clergy on the Copernican theory. 21 December 1613 Galileo writes a letter to Castelli submitting his ideas concerning the relationship of science and Scripture. February 1615 Lorini files a complaint with the Roman Inquisition against Galileo’s Copernican views. It includes a copy of Galileo’s 1613 letter to Castelli. April 1615 Bellarmino cautions scientists to treat Copernican views as hypothesis, not fact. December 1615 Galileo travels to Rome to defend his position. The trial of Galileo Galilei by the roman inquisition: a comprehensive overview 171 Journal of Social Sciences March, 2025, Vol. 8 Continuation Table 1 January 1616 Galileo argues the case for tidal theory, whereby tidal motion is proof that the earth is not stationary. February 1616 A committee of advisors to the Inquisition declares that heliocentric theory is absurd and formally heretical. 26 February 1616 Bellarmino warns Galileo not to hold, teach or defend Copernican theory. 5 March 1616 The Congregation of the Index bans Copernicus’s work until corrected. The Dominican friar Niccolo Lorini (1544–1617), a professor of ecclesiastical history at the University of Florence, denounced Galileo’s Copernican views. He was the first member of the clergy to publicly disagree with Copernican theory in November 1613. On 21 December 1613, Galileo wrote to the Benedictine friar Benedetto Castelli (1578–1643), a professor of mathematics at the University of Pisa, presenting his views regarding the relationship between science and scripture. In February 1615, Lorini filed a formal complaint with the Roman Inquisition against Galileo’s Copernican views and attached a copy of Galileo’s letter to Castelli. In April 1615, the Cardinal Bellarmino, a leading figure in the CounterReformation, cautioned scientists on behalf of the Holy Office to treat Copernican views as a hypothesis, not as fact. By his own will, Galileo travelled to Rome in December 1615 to defend his position. In January 1616, he argued that tidal motion was produced solely by the earth’s motion, that is, that the earth is not stationary. Following the statement of position by the committee of advisors to the Inquisition – which, in February 1616, declared that the heliocentric view of the universe was absurd and formally heretical – Bellarmino admonished Galileo on 26 February 1616 not to hold, teach, defend or discuss Copernican theory orally or in writing, to which Galileo agreed. On 5 March, the Congregation of the Index banned Copernicus’s De revolutionibus orbium coelestium (On the revolution of celestial spheres) [8] until corrections were made. Soon after, Galileo met with Pope Paul V (1550–1621), who assured Galileo that he was safe from persecution as he was held in high esteem. In collaboration with Mario Guiducci (1583–1646), Galileo published the Discorso delle comete (Discourse on the comets) in 1619 [9], months after three comets appeared, prompting widespread interest in their nature. In 1623, Galileo published Il Saggiatore (The Assayer) [10], which he dedicated to Cardinal Maffeo Barberini (1568–1644) who had just been elected the new pontiff, and “who was much more favourably disposed toward intellectuals and their work than his predecessor [Pope Gregory XV (1554–1623)] had been” [11: 466]. In 1624, Galileo had six audiences with Urban VIII (the former Cardinal Maffeo Barberini) and met other influential cardinals. The Pope directed Galileo to discuss and treat Copernican theory only as a mathematical hypothesis. By April 1630, Galileo completed his Dialogo sopra i due massimi sistemi del mondo, Tolemaico e Copernicano (Dialogue concerning the two chief world systems, Ptolemaic and Copernican), hereafter referred to as the Dialogue [12]; two months earlier, Urban VIII bestowed Galileo with an annual pension of 40 scudi. Figure 1 (left) shows the frontispiece of the Dialogue by Stefan Della Bella (1610–1664) while Figure 1 (right) is the title page of the work. By June 1630, Galileo had obtained conditional approval from the Secretary of the Vatican for its publication [1]. 172 L. Bianco Journal of Social Sciences March, 2025, Vol. 8 Figure 1. Dialogue: Frontispiece by Stefan Della Bella (1610–1664) (left); title page (right) [13] (online version is in colour). Linder’s chronology for the pre-trial phase is given in Table 2. The commencement of this phase can be attributed to the printing of the Dialogue in February 1632. By summer of the same year, its distribution was halted and Urban VIII set up a special commission to examine the publication. Based on the commission’s feedback, the pontiff referred Galileo’s case to the Roman Inquisition and a summons was issued. On receiving it in October 1632, Galileo requested the trial be held in Florence; the request was not upheld by the Inquisition, which was presided over by Urban VIII, in November 1632. The following month he submitted a statement by three physicians that he was not fit to travel to Rome. The Inquisition rejected this statement and declared that if Galileo did not travel to Rome voluntarily, he would be “brought a prisoner in irons to Rome” [4, p. 186]. Galileo arrived in Rome on 13 February 1633 and was accommodated at the residence of the Tuscan ambassador. He was introduced to Cardinal Francesco Barberini (1597–1679), a nephew of Urban VIII. The Cardinal “gave him [Galileo] a friendly hint … that he had better keep very retired in the ambassador’s house, not receive anyone, nor be seen out of doors” ([4, p. 192], according to dispatches from Niccolini to Cioli of 16 and 19 February 1633). Table 2 Chronology: pre-trial phase (After [1]) Date Event February 1632 Dialogue concerning the two chief world systems is printed. Summer 1632 The distribution of the Dialogue is halted by Urban VIII, who empowers a special commission to examine the book. September 1632 Based on the report of the special commission, the Pope refers Galileo’s case to the Roman Inquisition. The trial of Galileo Galilei by the roman inquisition: a comprehensive overview 173 Journal of Social Sciences March, 2025, Vol. 8 Continuation Table 2 October 1632 Galileo receives a summons to appear before the Inquisition; he requests the trial be held in Florence. November 1632 Galileo’s request is turned down. December 1632 Three physicians declare that Galileo is not fit to travel. The Inquisition rejects this declaration and asserts that if he does not travel to Rome voluntarily he will be arrested and brought in chains. 13 February 1633 Galileo arrives in Rome. He is allowed to stay at the home of the Tuscan ambassador and is advised to stay indoors and not to meet anybody. 4. The trail of Galileo On 12 and 30 April 1633, Galileo was interrogated by the Roman Inquisition, by the Dominican Vincenzo Maculani da Firenzuola (1578–1667), and formally charged on 10 May [6]. He was kept for two weeks in the building of the Inquisition. It is true that he was restricted to a confined place, and thus his confinement is referred to by Linder as imprisonment [1], but Galileo was placed in a comfortable apartment in the Holy Office fiscal's private residence, a layout sketch of which was reproduced by Gebler [4, p. 209]. This accommodation was far from a prison. After the first session, Firenzuola’s strategy was to induce Galileo “to enter a guilty plea judicially” [4: 213] in exchange for a lenient sentence. During the second session, Galileo declared that he overstated the case in the previous session. Figure 2 shows an 1857 painting by Cristiano Banti (1824–1904) which depicts Galileo during a session with Firenzuola, who is standing at the table. The trial was then held. Figure 2. Banti, Galileo facing the Roman Inquisition [14] (online version is in colour). 174 L. Bianco Journal of Social Sciences March, 2025, Vol. 8 Figure 3, a painting of 1847 by Joseph-Nicolas Robert-Fleury (1797–1890), portrays Galileo before the Holy Office. On 22 June 1633, Galileo was sentenced to life imprisonment, which was later commuted to house arrest. Seven out of the ten cardinal-inquisitors presiding at his trial signed the sentence (Table 3); Cardinal Barberini did not sign it. Galileo signed a formal recantation and was kept under house arrest at the residence of a former disciple and friend, the Archbishop of Siena. Figure 3. Robert-Fleury, Galileo before the Holy Office [15] (online version is in colour). Table 3 Judges at the trial of Galileo Name as stated in the sentence 1 Signature 2 Gasparo del titolo di S. Croce in Gierusalemme Borgia Fra Felice Centino del titolo di S. Anastasia, detto d’Ascoli F. Cardinalis de Asculo Guido del titolo di S. Maria del Popolo Bentivoglio G. Cardinalis Bentiuolus Fra Desiderio Scaglia del titolo di S. Carlo detto di Cremona Fr. Cardinalis de Cremona Fra Antonio Barberino detto di S. Onofrio Fr. Antonious Cardinalis S. Honuphrij Laudivio Zacchia del titolo di S. Pietro in Vincola detto di S. Sisto Berlingero del titolo di S. Agostino, Gessi B. Cardinalis Gypsius Fabricio del titolo di S. Lorenzo in pane e perna, Verospi Fr. Cardinalis Verospius Francesco di S. Lorenzo in Damaso Barberino Martio di S. Maria Nuova Ginetti Diaconi M. Cardinalis Ginettus 1 Based on [4, p. 230]; 2 based on [4, p. 234]. The trial of Galileo Galilei by the roman inquisition: a comprehensive overview 175 Journal of Social Sciences March, 2025, Vol. 8 In its sentence, the Inquisition noted that Galileo [4, p. 231]: 1. “denounced to this Holy Office for holding as true the false doctrine [of a heliocentric system of the universe] taught by many”; 2. had “disciples to whom you taught the same doctrine”; 3. held “correspondence with certain mathematicians of Germany concerning the same”; 4. printed “certain letters, entitled ‘On the Solar Spots’, wherein you developed the same doctrine as true”; and 5. replied “to the objections from the Holy Scriptures … by glossing the said Scriptures according to your own meaning: and whereas there was thereupon produced the copy of a document in the form of a letter, purporting to be written by you to one formerly your disciple, and in this divers propositions are set forth, following the hypothesis of Copernicus, which are contrary to the true sense and authority of Holy Scripture”. In 1616, Galileo agreed to comply with the order to abandon “he said false opinion, and not in future to defend or teach it in any way whatsoever, neither verbally nor in writing” [4, p. 231]. The Dialogue renewed the doctrine which he recanted. Based on Galileo’s confession, the Roman Inquisition found him “vehemently suspected of heresy, namely of having believed and held the doctrine – which is false and contrary to the sacred and divine Scriptures” [4, p. 233]. Based on these and on Galileo’s pronouncement that Copernican doctrine was erroneous and heretical, the Holy Office placed him under house arrest until his death and requested him “for three years to come you repeat once a week the seven penitential Psalms” [4, p. 234]. 5. Final comments Galileo consented in 1616 to abide by the order of the Roman Inquisition to give up his belief in a heliocentric system of the universe and to never again support or propagate it, either orally or in writing. The doctrine he renounced was revived in the Dialogue. The Roman Inquisition decided in June 1633 that he strongly suspected of heresy, specifically of believing and holding this belief which conflicts with the Scriptures. In December 1633, he was permitted to return to his home in Arcetri, Florence, where he lived under house arrest until his demise on 8 January 1642. He continued his writing and met visitors at his residence, including John Milton (1608–1674). His significant publication, Discorsi e dimostrazioni matematiche intorno a due nuove scienze (Discourses and mathematical demonstrations relating to two new science) [16], was published in 1638. Acknowledgments. The author would like to thank Professor Kevin Aquilina, former Dean of the Faculty of Laws (University of Malta), for his valuable comments and suggestions on an earlier draft of this paper. References 1. Linder, D.O. The Trial of Galileo: A chronology. In: Famous Trial. Available online: https://www.famoustrials.com/galileotrial/1015-chronology (accessed on 10 January 2025). 2. de Santillana, G. The Crime of Galileo. University of Chicago Press, Chicago, USA, 1962, pp. 117-281. 3. Pagano, S.M., Luciani, A.G. I documenti del processo di Galileo Galilei. Rome: Pontifical Academy of Sciences, 1984, pp. 63-248. 4. von Gebler, K. Galileo Galilei and the Roman Curia. Trans. and edited by Jane Sturge. London: Kegan Paul, 1879, pp. 175-248. 176 L. Bianco Journal of Social Sciences March, 2025, Vol. 8 5. Drake, S. Galileo. New York: Hill and Wang, 1980, pp. 73-79. 6. Kelly, H. A. Galileo’s Non-Trial (1616), Pre-Trial (1632–1633), and Trial (May 10, 1633): A Review of Procedure, Featuring Routine Violations of the Forum of Conscience. Church History 2017, 85(4), pp. 724761. https://doi.org/10.1017/S0009640716001190 7. Galilei, G. Istoria e Dimostrazioni intorno alle Macchie Solari. Rome: Accademia dei Lincei, 1613. 8. Nicolaus Copernicus, De revolutionibus orbium coelestium. Nuremberg: Johannes Petreius, 1543. 9. Galilei and M. Guiducci, Discorso delle comete. Pietro Cecconcelli, Florence, 1619. 10. Galileo, G. Il Saggiatore. Rome: Giacomo Mascardi, 1623. 11. Ravindra, R. Galileo Galilei. In: The Encyclopaedia of Religion. Editor in Chief Mircea Eliade. New York: Macmillan Publishing Co., 1987, 5, pp. 465-467. 12. Galileo, G. Dialogo sopra i due massimi sistemi del mondo, Tolemaico e Copernicano. Florence: Giovanni Batista Landini, 1632. 13. Landini, G.B. Frontispiece (by Stefan Della Bella) and title page of Galileo Galilei’s Dialogue Concerning the Two Chief World Systems, published by Giovanni Battista Landini in 1632 in Florence. 1632. [image]. Available online: https://upload.wikimedia.org/wikipedia/commons/c/ca/Galileos_Dialogue_Title_Page.png (accessed on 10 January 2025). 14. Banti, C. Galileo facing the Roman Inquisition. 1857. [image]. Available online: https://commons.wikimedia.org/wiki/File:Galileo_facing_the_Roman_Inquisition.jpg#mw-jump-to-license (accessed on 10 January 2025). 15. Robert-Fleury, J.N. Galileo before the Holy Office. 1847. [image]. Available online: https://commons.wikimedia.org/wiki/File:Galileo_before_the_Holy_Office_-_Joseph-Nicolas_RobertFleury,_1847.png (accessed on 10 January 2025). 16. Galileo, G. Discorsi e dimostrazioni matematiche intorno a due nuove scienze. Leiden: Lodewijk Elzevir, 1638. Annex: Galileo Galilei’s Sentence of the Roman Inquisition (Reproduced from [4, pp. 230-234]) We, Gasparo del titolo di S. Croce in Gierusalemme Borgia; Fra Felice Centino del titolo di S. Anastasia, detto d’Ascoli; Guido del titolo di S. Maria del Popolo Bentivoglio; Fra Desiderio Scaglia del titolo di S. Carlo detto di Cremona; Fra Antonio Barberino detto di S. Onofrio; Laudivio Zacchia del titolo di S. Pietro in Vincola detto di S. Sisto; Berlingero del titolo di S. Agostino, Gessi; Fabricio del titolo di S. Lorenzo in pane e perna, Verospi, chiamato Prete; Francesco di S. Lorenzo in Damaso Barberino, e Martio di S. Maria Nuova Ginetti Diaconi; by the grace of God, cardinals of the Holy Roman Church, Inquisitors General, by the Holy Apostolic see specially deputed, against heretical depravity throughout the whole Christian Republic. Whereas you, Galileo, son of the late Vincenzo Galilei, Florentine, aged seventy years, were in the year 1615 denounced to this Holy Office for holding as true the false doctrine taught by many, that the sun is the centre of the world and immovable, and that the earth moves, and also with a diurnal motion; for having disciples to whom you taught the same doctrine; for holding correspondence with certain mathematicians of Germany concerning the same; for having printed certain letters, entitled “On the Solar Spots”, wherein you developed the same doctrine as true; and for replying to the objections from the Holy Scriptures, which from time to time were urged against it, by glossing the said Scriptures according to your own meaning: and whereas there was thereupon produced the copy of a The trial of Galileo Galilei by the roman inquisition: a comprehensive overview 177 Journal of Social Sciences March, 2025, Vol. 8 document in the form of a letter, purporting to be written by you to one formerly your disciple, and in this divers propositions are set forth, following the hypothesis of Copernicus, which are contrary to the true sense and authority of Holy Scripture: This Holy Tribunal being therefore desirous of proceeding against the disorder and mischief thence resulting, which went on increasing to the prejudice of the Holy Faith, by command of his Holiness and of the most eminent Lords Cardinals of this supreme and universal Inquisition, the two propositions if the stability of the sun and the motion of the earth were by the theological “Qualifiers” qualified as follows: The proposition that the sun is the centre of the world and does not move from its place is absurd and false philosophically and formally heretical, because it is expressly contrary to the Holy Scripture. The proposition that the earth is not the centre of the world and immovable, but that it moves, and also with a diurnal motion, is equally absurd and false philosophically, and theologically considered, at least erroneous in faith. But whereas it was desired at that time to deal leniently with you, it was decreed at the Holy Congregation held before his Holiness on the 25th February, 1616, that his Eminence the Lord Cardinal Bellarmine should order you to abandon altogether the said false doctrine, and, in the event of your refusal, that an injunction should be imposed upon you by the Commissary of the Holy Office, to give up the said doctrine, and not to teach it to others, nor to defend it, nor even discuss it; and failing your acquiescence in this injunction, that you should be imprisoned. And in execution of this decree, on the following day, at the Palace, and in the presence of his Eminence, the said Lord Cardinal Bellarmine, after being gently admonished by the said Lord Cardinal, the command was intimated to you by the Father Commissary of the Holy Office for the time before a notary and witness, that you were altogether to abandon the said false opinion, and not in future to defend or teach it in any way whatsoever, neither verbally nor in writing; and upon your promising to obey you were dismissed. And in order that a doctrine so pernicious might be wholly rooted out and not insinuate itself further to the grave prejudice of Catholic truth, a decree was issued by the Holy Congregation of the Index, prohibiting the books which treat of this doctrine, and declaring the doctrine itself to be false and wholly contrary to sacred and divine Scripture. And whereas a book appeared here recently, printed last year at Florence, the title of which shows that you were the author, this title being: “Dialogue of Galileo Galilei on the Two Principal Systems of the World, the Ptolemaic and the Copernican”; and whereas the Holy Congregation was afterwards informed that through the publication of the said book, the false opinion of the motion of the earth and the stability of the sun was daily gaining ground, the said book was taken into careful consideration and in it there was discovered a patent violation of the aforesaid injunction that had been imposed upon you, for in this book you have defended the said opinion previously condemned and to our face declared to be so, although in the said book you strive by various devices to produce the impression that you leave it undecided, and in express terms as probable: which however is a most grievous error, as an opinion can in no wise be probable which has been declared and defined to be contrary to Divine Scripture: Therefore by our order you were cited before this Holy Office, where, being examined upon your oath, you acknowledged the book to be written and published by you. You confessed that you began to write the said book about ten or twelve years ago, after the