When The Judge is an Inquisitor: Summary of “The Earth Moves: Galileo and the Roman Inquisition” by Dan Hofstadter

In the introductory Author’s Note to The Earth Moves, Dan Hofstadter claims that he is “primarily interested in the arts” rather than the sciences, and that “Galileo’s position within the general context of Baroque civilization has not much concerned historians of science.” Hofstadter promises to “offer a brief picture” of that position. Instead, he devotes only a small portion of his narrative to placing Galileo into the context of the Baroque, but he does produce a taut, almost lawyer-like description of Galileo’s famous confrontation with the Inquisition.

Modern dramatists like Bertolt Brecht have portrayed the proceedings before the Roman Inquisition as a sort of 17th century Scopes monkey trial, where science confronted irrational religion and Biblical literalism. Hofstadter demonstrates that this approach makes for good theater but inaccurate history.

Most modern readers may not be aware of the sequence of the key events that led to Galileo’s dispute with his church. Keep these dates in mind as you read what follows:

1517: Martin Luther publishes his 95 Theses, initiating the Protestant Revolution and emphasizing the ability of individuals to interpret the Bible.

1543: Copernicus (a Polish Catholic priest) publishes De Revolutionibus Orbium Coelestium, (On the Revolution of the Heavenly Spheres) proposing a model of the cosmos with the sun rather than the earth at its center.

1545-1563: The Council of Trent initiates the Catholic Church’s Counter Revolution, responding to the Protestant Revolution, and rules that only theologians, and not members of the laity, could interpret the Bible.

1609: Galileo builds some of the first powerful telescopes, enabling him to see that the surface of the moon was not smooth, that Venus exhibited phases like the moon, and that Jupiter had at least four moons of its own.

Note that the Copernican model of the cosmos had been known and discussed in intellectual and astronomical circles in Europe for 66 years when Galileo first turned his telescopes to the heavens.

Galileo did not invent the telescope, but he built far better instruments than any of his contemporaries. Hofstadter goes into substantial detail to show how Galileo’s design improved upon that of his predecessors. He also shows that Galileo’s were difficult to use. Moreover, Galileo was loath to allow others to use his instruments because there was no strong intellectual property protection available, and he feared others would copy his designs and erode his near monopoly. Thus Galileo was able to see things that his rival scientists and churchmen could not see.

Galileo’s telescope (Picture from Museum of Science, Florence)

The Catholic Church took the position that the heliocentric model of the cosmos was contrary to scripture, which in several places describes the sun as moving around the earth from east to west, except for the notable exception when it stopped in its path to enable Joshua to complete his conquest of Jericho.

Galileo’s telescopic discoveries did not actually prove the heliocentric model, but it did enhance the model’s plausibility. The mountains and valleys he saw on the moon showed that Aristotle’s conception of the heavenly bodies as perfect crystalline spheres was incorrect. The phases of Venus made more sense if it were rotating around the sun rather than the earth. And Jupiter’s moons clearly showed that at least four heavenly objects revolved around something other than the earth.

Galileo’s journal entries describing his revolutionary discovery of four moons orbiting Jupiter, from NASA science education site

In any event, by 1616 the Inquisition became concerned about some of Galileo’s discoveries and essays sympathetic to the idea of the earth’s motion. They issued a decree condemning Copernicanism as “foolish and absurd in philosophy, and formally heretical” because it contradicted scripture. They were suspicious of Galileo’s thinking on this matter even though he had not published an explicit defense of Copernicus. [A private letter he wrote in 1613 indicates that he was a convinced Copernican.] Cardinal Bellarmine was intelligent enough to understand that the Copernican model was simpler and mathematically more elegant than the earth centric (Ptolemaic) model. Yet because of the scriptural references, he felt that the Church could not adopt a new model unless the proof for it was incontrovertible. He warned Galileo that he could look at the heliocentric model as a mathematical curiosity that could be considered “suppositionally,” but he admonished the scientist not to hold, teach, or defend it.

Cardinal Bellarmine

Cardinal Bellarmine

Galileo was headstrong and truculent, and he was convinced that the heliocentric model was correct. Moreover, he was a better theologian than anyone in the Roman curia at the time. He remained a devout Catholic, but he argued that the Bible was written for simple people as well as for sophisticated intellectuals and that men could divine God’s plan through His works as well as through His words. If God’s words (scripture) seemed to contravene what was manifest in His works, the words would have to be interpreted in some non-literal way.

In 1632 Galileo published Dialog Concerning the Two Chief World Systems. In order to pass censors, the book takes the form of a Platonic dialog in which the interlocutors discuss the relative merits of the Ptolemaic and heliocentric models of the cosmos. However, the spokesman for the Ptolemaic model is clearly a simpleton (named, aptly, Simplicio), whereas the spokesman for the Copernican model is erudite and trenchant.

The Roman inquisitors were not so dense that they could not infer the obvious thrust of Galileo’s arguments. Accordingly, they demanded that he appear before them. If the Inqusition’s procedures had been anything like an American court’s, the stage would have been set for a dramatic confrontation of ideas. However, as Hofstadter points out, the Inquisition had no interest in debating the relative scientific merits of either position. It mattered not one whit to the Inquisitors whether Galileo’s scientific position was correct. The only issue before them was one of obedience: did he “hold, teach, or defend” the Copernican view. And if they found that he had had the temerity to attempt to interpret the Bible, he would be guilty of violating the teachings of the Council of Trent.

Hofstadter asserts that Galileo was naïve to think that he could convince the Inquisitors through the strength of his scientific arguments. Indeed, the records of the proceedings contain only a few desultory references to the merits of the scientific issues. The only thing that injected some doubt into the outcome was some political maneuvering Galileo’s friends attempted to influence the pope. Fortunately for Galileo, he was not charged with heresy, a capital offense, but merely “rashness,” a lesser offense. The verdict was never really in doubt, but the punishment was less severe that it might have been. Because he ultimately recanted and admitted his “error,” Galileo was only confined to a sort of house arrest for the rest of his life.

Holy Relic of Science: Galileo’s finger, on display at the Museo di Storia del Scienza in Florence, Italy

Evaluation: Hofstadter’s book is even-handed, thorough, and sympathetic. He shows Galileo in all his brilliance and pig-headedness. As promised in the introduction, he makes a small effort to set the Galileo trial in the context of the Baroque period of art, with references to the construction of great domed cathedrals, but I’m not sure these references contribute much to the story. He is, however, effective in showing that the Copernicans had difficulty in overturning not only Ptolemy’s cosmology but also the world-view of Dante’s Divine Comedy, which was shared by most people of the time. In all, this is a solid historical narrative and a good introduction to an important event in the history of science and its relation to religion and the law.

Rating: 4/5

Published by W. W. Norton & Company, inc., 2009