The Prohibition of the Heliocentric Theory (1616)

In order to understand the investigation process and Galilei's trail we recommend to look at - Lexicon Galileo's trial.

Following Galileo's new discoveries by means of the telescope, beginning in 1610, there was increased interest in astronomy in general and in the geocentric (Copernican) theory in particular.

In his discoveries, writings and speeches, Galileo contributed to the plausibility of the Copernican theory. He even claimed that in light of his observations, Aristotle himself would have been convinced that the heliocentric theory was true.

The Aristotelian philosophers had good reasons for not agreeing with this claim. The heliocentric theory found new supporters, who saw it as a physical description of the world, and not just an astronomical method of calculation. These supporters conveyed their ideas both by word of mouth and in writing.

The success of the heliocentric theory and the discussions which centered on it, engendered resistance among the Aristotelian natural philosophers (those who upheld Aristotelian Physics) and also among the clergy. Very quickly, a new weapon was leveled against supporters of the new theory, namely the authority of Scripture. Those who objected to the Copernican theory claimed that it contradicts both Scripture and the Church's interpretation of Scripture. The main item presented by these opponents as scriptural evidence that the sun moves, was the description of the miracle of Joshua in the battle of Gibeon, where it was said:

"Then spake Joshua... Sun stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon... So the sun stood still in the midst of heaven, and hastened not to go down about a whole day." (Joshua, X 12-13).

These claims were first heard in Florence and Pisa, where the heliocentric theory was successful, and later spread to Rome too.

Galileo responded to the claims against the theory by explaining how the Scripture may be explained according to the Copernican theory. He first did so in 1613, in a letter to his student Castelli, which was widely distributed. He then expanded on these ideas two years later in a letter to the Duchess Christina. Galileo's claims and the claims of his opponents, may be found in the Interpretation of the Holy Scriptures and the Copernican Theory. Galileo's reaction only increased the polemics surrounding this issue and the Church's resistance.

At the beginning of 1615, the Inquisition received a complaint against Galileo, on account of the liberties he had taken in interpreting Scripture in his letter to Castelli. An official Church investigation found nothing offensive to the Catholic faith in the letter. The matter could have been settled then and there, were it not for additional complaints made against Galileo regarding his writings and utterances in support of the theory according to which the earth revolves around the sun. At this stage, the threat against Galileo was not great, because Copernicanism had not yet been prohibited by the Church. In fact, the main bone of contention was the status of the heliocentric theory, and whether it would be deemed to contradict the Christian Catholic faith? This declaration would have meant prohibition of the theory and would have prevented any possibility of continued attempts to determine it. It should be remembered that up until 1615, more than seventy years after the publication of Copernicus' theory, Catholics had not been prohibited from holding this theory.

Galileo traveled to Rome in order to try to exert his influence with regard to two issues. He wished to challenge the personal accusations leveled against him, rumors of which had reached him (the investigation was conducted in secrecy) and to influence the Church not to ban the Copernican theory. He succeeded in his first mission, the complaints against him being dismissed without trial, but failed in the second. In February 1616, a special Theological Advisory Committee determined that the heliocentric theory contradicts the Catholic faith. With regard to the claim that the sun lies motionless at the center of the world, the committee determined that it is: "Philosophically (i.e., scientifically) foolish and absurd, and is considered official heresy because it explicitly contradicts the meaning of Scripture in many places, in terms of the verbal significance of the words and in terms of the accepted interpretation and understanding of the Church Fathers and the Doctors of Theology."The claim that the earth revolves around the sun was considered only "a mistake of faith."

Following this decision, Galileo was summoned to Cardinal Bellarmine, the leading theologian of the period, who informed him of this decision and made it clear that it was now prohibited to defend or subscribe to this theory. According to an unsigned document found in the Church, Bellarmine also forbade Galileo to teach the Copernican theory. (See an unsigned document). The question of whether an additional prohibition with regard to teaching the theory had indeed been imposed on Galileo or not, was one of the central issues of Galileo's trial in 1633. There is no doubt that in 1616, no steps were taken against Galileo. In the meantime, rumors had spread that the Inquisition had tried Galileo and denounced his views (the Inquisition's trials were held in secrecy). In order to prove his innocence, Galileo obtained an official letter from Bellarmine, explicitly stating that Galileo had not been accused. This letter was main piece of evidence in Galileo's 1633 trial.

Following the decision of the Theological Advisory Committee, the Congregation of Church Theologians issued a public edict which declared the heliocentric theory to be false. This statement was less severe than the original one which had referred to the theory as heresy. The edict suspended the distribution of Copernicus' book and an additional book, until the proper corrections had been introduced. In 1620, these corrections were published, explaining that the books do not claim that the earth actually revolves around the sun, but only that a mathematical description of its movement constitutes a merely mathematical way to view the observed phenomena. The book written by Foscarini, a professor of theology and the head of a monastery who explained how the Copernican theory does not contradict the Scripture, was banned outright. Galileo's books were not mentioned at all.

The unsigned document according to which Galileo was prohibited from teaching the Copernican theory:

Special Injunction (26 February 1616)

Friday, the 26th of the same month.

At the palace of the usual residence of the said Most Illustrious Lord Cardinal Bellarmine and in the chambers of His most Illustrious Lordship, and fully in the presence of the Reverend Father Michelangelo Segizzi of Lodi, O.P. and Commissary General of the Holy Office, having summoned the above-mentioned Galileo before himself, the same Most Illustrious Lord Cardinal warned Galileo that the above-mentioned opinion was erroneous and that he should abandon it; and thereafter, indeed immediately, before me and witnesses, the Most-Illustrious Lord Cardinal himself being also present still, the aforesaid Father Commissary, in the name of His Holiness the Pope and the whole Congregation of the Holy Office, ordered and enjoined the said Galileo, who was himself still present, to abandon completely the above-mentioned opinion that the sun stands still at the center of the world and the earth moves, and henceforth not to hold, teach, or defend in any way whatever, either orally or in writing; otherwise the Holy Office would start proceedings against him. The same Galileo acquiesced in this injunction and promised to obey.

Done in Rome at the place mentioned above, in the presence, as witnesses, of the Reverend Badino Nores of Nicosia in the kingdom of Cyprus and Agostino Mongardo from the Abbey of Rose in the diocese of Montepulciano, both belonging to the household of the said Most Illustrious Lord Cardinal.

(Sections from the document pages 147-8).