Saturday, April 01, 2023

Galileo on the Harmony Between Biblical Faith and Scientific Reason: Separating "How One Goes to Heaven" From "How Heaven Goes"?

Recently, an article in the New York Times noted that 30 asteroids have been officially named after Jesuit astronomers.  Last month, three new ones were named after three Jesuit priests:  565184 Janusz for the Rev. Robert Janusz, a polish priest and physicist, 551878 Stoeger for the Rev. William R. Stoeger (1943-2014), an American priest, and 562971 Johannhagen named for the Rev. Johann Georg Hagen (1847-1930), an Austrian American, who is said in the naming citation to have "devised several ingenious experiments at the Vatican to demonstrate the rotation of the Earth, directly confirming the theories of Copernicus and Galileo."  All three of these men have worked in the Specola Vaticana (the Vatican Observatory), just off the papal gardens at Castel Gandolfo, close to Rome.  The Vatican Observatory was first established by Pope Leo XIII in 1891 to support advances in the science of astronomy.

This must surprise many of us who have been taught the story about how the Catholic Church's Inquisition in 1633 punished Galileo Galilei with imprisonment for teaching that the Earth rotates and moves around the Sun and thus committed the heresy of denying the Bible, which seems to teach that the Earth is unmoved at the center of the cosmos, with the Moon, the Sun, and the planets moving around the Earth.

Actually, Galileo showed how there need be no conflict between Biblical faith and scientific reason, as long as one sees that the Bible teaches us "how one goes to Heaven" but not "how heaven goes."  Remarkably, the Catholic Church--particularly under the leadership of Pope John Paul II in 1992--has accepted this teaching of Galileo and admitted that the punishment of Galileo by the Catholic Inquisition was wrong.  The Church has also adopted this teaching as supporting the liberal principles of religious liberty and scientific liberty.  This has allowed the Church to accept the scientific truth not only of Galilean astronomy but also of Darwinian evolution as consistent with the transcendent salvational truth of the Bible.  The official Catholic acceptance of Darwinian evolution came in 1996 with a statement by Pope John Paul II.  Protestants (like Francis Collins and Deborah Haarsma) have followed the lead of the Catholic Church in accepting "theistic evolution" or "evolutionary creation" as compatible with both Biblical truth and scientific truth.  What we see here is that even if the teaching of Galileo does not completely resolve the tension between Reason and Revelation, it does at least leave it open to free debate in a free society.


In 1543, Nicolaus Copernicus published his book On the Revolutions of the Heavenly Spheres, in which he updated the ancient Greek idea (of Pythagoras and others) that the Earth moves by rotating on its axis daily and by revolving around the Sun once a year.  This was rejected by the proponents of the Ptolemaic geocentric system with a stationary Earth at the center of the cosmos and the Sun and the planets revolving around the Earth.  The argument of Copernicus was mostly hypothetical:  if the Earth were in motion around the Sun, then the observed phenomena in the sky would result.  But Copernicus could not present enough empirical evidence to make his idea persuasive.

There were four kinds of objections to the Copernican system (see Finocchiaro 1989, 16-25).  The first was that it was epistemologically absurd because it denied our direct sensory experience of the world.  Throughout our lives, all of us perceive that the Earth is at rest, while the rest of the cosmos moves around the Earth.  Every day we see that the Sun rises in the east and sets in the west.  Of course, we know that our senses are sometimes deceived: a straight stick half immersed in water appears bent.  But we easily correct such perceptual illusions.  By contrast, it's hard to see how we could correct our perception of the Earth being at rest.  That would be such a radical deception of our senses that we would lose all confidence in our senses as a guide to truth.

The second objection was that the Copernican system was empirically false because it predicted some astronomical consequences that were not observed.  For example, if Copernicus was right, then the Earth must be a planet, the third planet circling the Sun, with physical properties like the other planets.  But according to the medieval model of the cosmos, the Earth differed in its elemental properties from the heavenly bodies.  The heavenly bodies were made of the element ether, which was weightless, luminous, and changeless, while the Earth was made of rocks, water, and air, which were (positively or negatively) weighted, dark, and changeable.  Also, if Copernicus was right, then the planet Venus should show phases similar to the Moon, and the planet Mars should show differing apparent brightness and size since Mars and the Earth revolve around the Sun at different rates.  Before the telescope, this kind of objection seemed to be empirically supported.

The third objection to the Copernican system was that it was physically impossible because it violated some of the fundamental principles of physics as it was known at the time.  That the Earth could rotate on its axis or revolve around the Sun seemed physically impossible because the natural motion of earthly bodies (rocks and water) was to move in a straight line to the center of the Earth.  There were three types of natural motion (as opposed to forced or violent motion): ether (the element of the heavenly bodies) moved eternally in a circular motion around the center of the cosmos; the elements air and fire moved in a straight motion away from the center of the cosmos; and the elements earth and water moved in straight motion to the center of the cosmos.  Every simple element could have one and only one natural motion.  Answering this objection required developing a new science of physics with new laws of motion, such as the law of inertia, the law of gravitational force, and the law of conservation of momentum.

The fourth objection to the Copernican system was that it was theologically heretical because it contradicted the literal meaning of the Bible and the unanimous biblical interpretations of the early Church Fathers.  For example, in Joshua 10: 12-13, the Bible tells us: "Then spoke Joshua to the Lord in the day when the Lord delivered up the Amorites before the children of Israel, and he said in the sight of Israel, 'Sun stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon.' And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies."  Protestants agreed with this biblical objection because of their literal interpretation of the Bible.  Catholics agreed with this biblical literalism, but they also agreed with the appeal to the Church Fathers because Catholics saw God's revelation through the work of the Holy Spirit in guiding both the authors of the Bible and the traditional theology of the Church.

Galileo tried to answer all four objections, but the biblical objection was the hardest to overcome, and that led to his condemnation by the Catholic Church's Inquisition.


In the fall of 1609, Galileo built the first astronomically useful telescope, and he used it to study the night sky.  In 1610, in his book The Starry Messenger, he published some of his discoveries: that the Moon, like the Earth, has a rough, rocky, and nonluminous surface, and that the planet Jupiter has at least four moons, and thus constitutes its own miniature planetary system.  Later he published other discoveries: that the planet Venus shows phases similar to the Moon; that the planet Mars shows large changes in brightness and apparent size; and that there are dark spots on the Sun that move in such a way as to suggest that the Sun rotates on its axis once a month.  In his published writings, Galileo did not explicitly indicate how this was evidence for the Copernican heliocentric system; but in his private correspondence, he was open about this.

In response to Galileo's new evidence for the Copernican system, the conservative supporters of the Ptolemaic system began to rely on biblical arguments based on biblical passages that apparently teach that the Sun revolves around the Earth, as in Joshua 10:12-13.  In December of 1613, Galileo responded to these biblical arguments in a letter to his friend Benedetto Castelli.  Although it was not published, this letter was widely copied and circulated.

Employing the traditional theological metaphor of God's "two books"--that God reveals His truth both in the books of the Holy Scripture as dictated by the Holy Spirit and in the book of Nature as governed by the laws of nature given by God that can be known by human reason--Galileo claimed that these two truths of the Bible and nature can never contradict each other (Galileo 1989a).  Whatever the Holy Spirit teaches in the Bible must be consistent with whatever scientists discover to be true about nature by sensory experience and necessary demonstration.  

But sometimes the literal meaning of the words of the Bible can contradict the findings of natural science.  And then one must see that the literal interpretation of the Bible is an error.  As guided by the Holy Spirit, the authors of the Bible often had to adapt what they said to the understanding of common people.  And so, for example, there are many biblical passages that "attribute to God feet, hands, and eyes, as well as bodily and human feelings like anger, regret, hate, and sometimes even forgetfulness of things past and ignorance of future ones," because common people tend to have such anthropomorphic conceptions of God; but surely to take this as a literally true account of God would be blasphemous (Galileo 1989a, 50). Similarly, the Bible might speak of the Sun revolving around the Earth, because common people would be unable to comprehend the truth of the Earth's moving and the Sun standing still.  The intention of the Holy Spirit was not to teach natural science but to teach what was required for salvation; and so that salvific teaching was true, while much of what might be said about the natural world could be false if interpreted literally.

This Letter to Castelli provoked attacks on Galileo from some traditionalist Christians, and particularly some Dominican friars in Florence.  In December of 1614, Tommasco Caccini preached a Sunday sermon in a church in Florence arguing that Galileo was a heretic in contradicting the Bible.  In February of 1615, another Dominican--Niccolo Lorini--filed a written complaint against Galileo with the Inquisition in Rome, and he enclosed a copy of Galileo's letter to Castelli as evidence of heresy.  In March of 1615, Caccini appeared before the Roman Inquisition for a deposition, in which he claimed that Galileo's Copernican teaching denied the literal sense of the Bible as supported by the unanimous interpretation of the Church Fathers.

In response to these charges, Galileo wrote a series of essays in 1615, of which the most important was his Letter to the Grand Duchess Christina which elaborated the arguments from his letter to Castelli.  Today, these arguments from the Letter to Christina have been adopted by many Catholic and Protestant scientists as supporting their belief that biblical faith and natural science must be in harmony (see, for example, Block and Freeman 2019).

In the Letter to Christina, Galileo (1989b) continued to employ the "two books" metaphor and to argue that the harmony between those two books depends on seeing that the true meaning of the Bible is not the pure literal meaning.  He continued to use the Bible's anthropomorphic descriptions of God (as having hands, feet, eyes, and bodily sensations and feelings) as illustrating how the biblical authors accommodated their writing to the mistaken understanding of common people.  And he continued to argue that the primary purpose of the Bible is teaching the way to salvation, which does not require any true scientific teaching about the natural world.  (I have written previously about how Charles Darwin also employed the "two books" metaphor to support the compatibility of biblical faith and evolutionary science.)

Galileo captured the gist of his reasoning in a clever aphorism that has been one of Galileo's most often quoted remarks: "the intention of the Holy Spirit is to teach us how one goes to heaven and not how heaven goes" (Galileo 1989b, 96).

This plays off of the ambiguity in the word "heaven."  The Italian word cielo, the Latin word caelum, and the English word "heaven" all have a double meaning.  According to the Oxford English Dictionary, the primary meaning of "heaven" is "the expanse in which the sun, moon, and stars are seen, (esp. in earlier use) regarded as having the appearance of a vast vault arched over the earth; the sky, the firmament."  The secondary meaning is "the abode of God and of the angels and persons who enjoy God's presence, traditionally regarded as being beyond the sky; the final abode of the redeemed after their life on earth; a state or condition of being or living with God after death; everlasting life.  Opposed to hell."

One interpretation of Galileo's Copernican Revolution as conveyed in his separation of "how one goes to heaven" from "how heaven goes" is to say that he separated heaven (as God's abode and the abode of the redeemed in the afterlife of immortality that can be known only by faith) from the sky (as the expanse of astronomical bodies and space that can known by natural science); and while these two realms of two kinds of truth must be separated, they are not contradictory; and the biblical believer can see them as two different expressions of one truth--God.

In making this argument for the harmony of biblical truth and scientific truth in the Letter to Christina, Galileo appealed to the authority of St. Augustine, which countered the charge that he was denying the teachings of the Church Fathers.  He quoted from Augustine's On the Literal Interpretation of Genesis as saying that "whenever the experts of this world can truly demonstrate something about natural phenomena, we should show it not to be contrary to our Scripture" (Augustine 1999, 1.21).  The Bible must be interpreted in such a way as to be consistent with human knowledge of the natural world, including the movements of the sun, the moon, and the planets.  After all, "it frequently happens that even non-Christians will have knowledge of this sort in a way that they can substantiate with scientific arguments or experiments" (1.19).  The authors of the Bible "knew about the shape of the sky whatever may be the truth of the matter.  But the Holy Spirit who was speaking through them did not wish to teach people about such things which would contribute nothing to their salvation" (II.20).  (Notice how this remark by Augustine is echoed in Galileo's quip about separating "how one goes to heaven" from "how heaven goes.")  The intention of the Holy Spirit was to teach people through the Bible not about the natural truth of the natural world but about the supernatural truth of salvation through the doctrines of "the resurrection of the dead, the hope of eternal life, and the kingdom of Heaven" (Augustine 1999, 1.19; Galileo 1989b, 112).

There are, however, at least three problems in Galileo's reasoning in his Letter to Christina--in his assumption that the divine reality of Heaven does not depend on any particular scientific conception of the cosmos, in his dismissal of the anthropomorphic depictions of God in the Bible, and in his claim that the Holy Spirit has clearly conveyed the way to salvation in Heaven through the revelation of the Bible in a manner that does not deny the truth of natural science.

The first problem is that since the medieval cosmic model (such as Dante depicted in The Divine Comedy) located Heaven in the Empyrean realm and Hell below the surface of the Earth, Galileo's scientific denial of that model denied the reality of Heaven and Hell.  Remarkably, Galileo's first public lecture as a young man was about the mathematical geography of Hell in Dante's Inferno, as if Hell were a real subterranean place deep in the Earth (Heilbron 2010, 28-33).  But then in the Letter to Christiana, he suggested that the way to the afterlife taught in the Bible belongs to the supernatural world known by religious faith as opposed to the natural world known by scientific reason (Galileo 1989b, 101). 

Must faith and science therefore be totally separated?  Or is it possible, as I have suggested in various posts, for science to study the natural history, the cultural history, and the individual psychology of religious beliefs in Heavenimmortalitythe afterlife, and the existence of God?

The second problem in Galileo's Letter to Christina is his assumption that the anthropomorphic image of God in the Bible as having a body is so absurdly blasphemous that this proves that the literal meaning of the Bible is often a mistaken interpretation.  This is dubious for two reasons.  While the Bible is full of passages describing God's body, nowhere does the Bible say that the literal meaning of these passages must not be taken seriously.  After all, from the beginning of the Bible, God is said to have created man in His own image and likeness, which is to say that God was in the image and likeness of man.  And in the New Testament, it is clearly taught that Jesus, the Son of God, has a perfect human body--that He is God incarnate ("in the flesh").

Recently, Francesca Stavrakopoulou has written a wonderful book--God: An Anatomy--in which she goes through the Bible to find accounts of God's body, from his head to his hands, feet, and genitals.  She points out, however, that when the ancient Jewish and Christian theologians came under the influence of Platonic Greek philosophy, they began to identify the God of the Bible with Platonic abstractions about the Divine as timeless, changeless, and immaterial.  God became a transcendent, invisible, and incorporeal being that was a distorted refraction of the original biblical image of God as an embodied being made in our own image.

The third problem in Galileo's Letter to Christina is his dubious assumption that the Holy Spirit will guide us to the correct interpretation of biblical revelation, and that this correctly interpreted teaching about the truths of faith will not conflict with the truths of science.  Previously, I have argued that the Holy Spirit has failed to convey that correct interpretation of biblical revelation that would resolve the creation/evolution debate among Christian believers.  Similarly, it seems that the Holy Spirit failed to persuade the Roman Inquisition that Galileo was correct in interpreting the Bible as compatible with Copernican astronomy.

Throughout 1615, the Roman Inquisition commissioned reports and took depositions pertaining to the charge that the Copernican system was heretical, and that Galileo was a heretic for teaching this.  In December of 1615, Galileo left his home in Florence to travel to Rome to try to clear his name and prevent the Inquisition from condemning Copernicanism.  He lodged at the Tuscan embassy in Rome for six months.  Since 1610, Galileo had been the philosopher and chief mathematician of the Grand Duke of Tuscany.

The Inquisition asked a group of theologians to prepare a report on Copernicanism.  On February 24, 1616, they submitted a report that concluded that the Copernican teaching was "foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture, according to the literal meaning of the words and according to the common interpretation and understanding of the Holy Fathers and the doctors of theology" (Finocchiaro 1989, 146).

On the following day, the Inquisition asked Cardinal Robert Bellarmine (a Jesuit priest and probably the most influential Catholic churchman of his time) to meet with Galileo and demand that he agree to abandon his Copernican opinions, and that if he did not acquiesce, he would be imprisoned.

The next day, Bellarmine met with Galileo and gave him a "special injunction . . . to abandon completely . . . the opinion that the sun stands still at the center of the world and the earth moves, and henceforth not to hold, teach, or defend it in any way whatever, either orally or in writing; otherwise the Holy Office [the Inquisition] would start proceedings against him.  The same Galileo acquiesced in this injunction and promised to obey" (Finocchiaro 1989, 147-48).

A few days later, Bellarmine reported to the Inquisition that the Congregation of the Index of Prohibited Books would decree that Copernicus's book On the Revolutions of the Heavenly Spheres would be suspended until it could be corrected.  Only a few lines of the book were changed.  Copernicus's book had been permitted for over 70 years.  But now it became the first book devoted entirely to science to be condemned, even if only temporarily until it was slightly revised, by the Congregation of the Index.  Anyone but Galileo could discuss the corrected book, as long as they called it only a hypothesis.

On March 12, Galileo reported to the Tuscan Secretary of State that he had met with Pope Paul V for three-quarters of an hour, and that the Pope had received him warmly and even told him that he should feel safe as long as the Pope lived.

Galileo began to receive letters from friends in Pisa and Venice reporting rumors that Galileo had been personally put on trial and condemned by the Inquisition.  To silence these rumors, Galileo asked Cardinal Bellarmine to write a statement certifying that he had not been formally condemned by the Inquisition.  Bellarmine wrote:

". . . we say that the above-mentioned Galileo has not abjured in our hands, or in the hands of others here in Rome, or anywhere else that we know, any opinion or doctrine of his; nor has he received any penances, salutary or otherwise.  On the contrary, he has only been notified of the declaration made by the Holy Father and published by the Sacred Congregation of the Index, whose content is that the doctrine attributed to Copernicus (that the earth moves around the sun and the sun stands at the center of the world without moving from east to west) is contrary to Holy Scripture and therefore cannot be defended or held" (Finocchiaro 1989, 153).

We see here that Galileo both won and lost his battle.  He won by escaping personal public condemnation by the Church.  But he lost the intellectual and theological debate over whether Copernican science was compatible with biblical faith.

In 1633, however, he would lose the whole battle when the Inquisition condemned him to abjuration, penance, and imprisonment for teaching the truth of Copernican science.  And yet, eventually, by 1992, he would be vindicated by the Church.

In my next post, I will look at the intellectual history of the "Galileo Affair," and I will suggest that its resolution--among both Catholic and Protestant Christians--followed a similar pattern for the "Darwin Affair" (the debate over whether Darwinian evolution is compatible with the Bible), so that in both cases Reason triumphed over Revelation among Christians, because they agreed that they needed to look to scientific reason to correct the Holy Spirit's interpretation of the Bible, so that they could see how Copernican astronomy and Darwinian biology do not deny their religious belief in the transcendent destiny of their souls; and therefore they could accept freedom of thought for scientists and philosophers in a Lockean liberal social order as posing no threat to their Christian pilgrimage in the world.


Augustine, Saint. 1999. The Literal Meaning of Genesis.  In Augustine, On Genesis, trans. Edmund Hill, 159-581. Hyde Park, NY: New City Press.

Block, David, and Kenneth Freeman. 2019. God and Galileo: What a 400-Year-Old Letter Teaches Us About Faith and Science. Wheaton, IL: Crossway.

Finocchiaro, Maurice, ed. 1989. The Galileo Affair: A Documentary History. Berkeley: University of California Press.

Galileo Galilei. 1989a. Letter to Castelli. In Maurice Finocchiaro, ed., The Galileo Affair: A Documentary History, 49-54. Berkeley: University of California Press.

Galileo Galilei. 1989b.  Letter to the Grand Duchess Christina.  In Maurice Finocchiaro, ed., The Galileo Affair: A Documentary History, 87-118.  Berkeley: University of California Press.

Heilbron, J. L.  2010. Galileo. Oxford: Oxford University Press.

Stavrakopoulou, Francesca. 2022. God: An Anatomy. New York: Knopf.

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