Great Astronomers: Galileo
Great Astronomers in Modern English
by Sir Robert S. Ball, 1895 (paraphrased by Leslie Noelani Laurio)
To view the table of contents for the rest of this book, click here.
Galileo Galilei. 1564-1642
Not only the first astronomer to use the telescope; he paved the way for the acceptance of Copernicus's heliocentric model of the universe.
Of all the famed astronomers, it would be hard to find one whose life had more interesting events and fluctuations than Galileo's. He was a patient investigator and a brilliant discoverer. He had some fascinating personal relationships, especially with his daughter, Sister Maria Celeste, who was a very exceptional woman. There was also the sad drama near the end of his life, when his work drew the criticism of the Inquisition.
There are many resources about Galileo's life to use for writing a biography. This chapter made use of the charming letters his daughter wrote to him from her convent. More than a hundred of them survived, and they are extraordinarily beautiful and touching and show how much his daughter loved him. There's also a collection called "The Private Life of Galileo," published by Macmillan in 1870; some facts for this chapter have come from that book. [The book is mostly his correspondence with his daughter; it is online at archive.org.]
Galileo was born at Pisa [Italy] on February 18, 1564. He was the oldest son of Vincenzo de Bonajuti de Galilei, a Florentine noble. Even so, the family lived in poverty and Galileo knew that he would need to learn some kind of profession to support himself. He inherited a love for music from his father, who was an excellent lute player. He also had some artistic ability, and entertained the idea of a career as a painter. But his father decided he should study medicine. So, at the age of seventeen, with a knowledge of Greek and Latin as well as art, he was enrolled at the University of Pisa.
It was here at the University of Pisa that Galileo gained some understanding of mathematics. He found math so interesting that he begged to be allowed to study geometry, so his father reluctantly let him hire a math tutor. He was concerned that Galileo might be distracted from his medical studies, and his concerns weren't unfounded. Euclid's book of geometry propositions engrossed Galileo so much that his father decided to let the tutor go so his son could put his mind back on his medical lessons. But now it was too late. Galileo had caught on so quickly that he no longer needed a tutor; he was able to study geometry on his own. Soon he had grasped Euclid's 47th proposition ["In right-angled triangles the square on the side opposite the right angle equals the sum of the squares on the sides containing the right angle;" read more here] and he kept going until he had mastered all six books of Euclid -- a considerable feat in those days. [And in these days, too!]
But his diligence and brilliance didn't win him much approval with the Pisa University authorities. Back then, Aristotle's ideas were considered the epitome of human wisdom in natural science and everything else. It was considered the duty of every scholar to learn Aristotle by heart. Any student who dared to doubt or even question Aristotle's doctrines was considered extremely arrogant. But young Galileo was bold and reckless enough to think through his own ideas about how nature worked. He wouldn't blindly accept anyone else's principles until he could test them himself to see if they were true. His teachers started to think of him as a misguided young fool, even though they couldn't help respecting his energy and diligence as he collected all the knowledge he could find.
We are so accustomed to pendulums in clocks that we forget it was Galileo who invented them. He was sitting in the Cathedral at Pisa one day and his attention was drawn to a chandelier swinging from the ceiling. He noticed that whether the chandelier made a wide arc or a short one, the time it took to get from one side to the other was the same. To his observant mind, that made it useful for marking time. So Galileo constructed the first timepiece controlled by pendulum motion. He intended it as a tool for doctors to measure the pulse rates of their patients. [View a replica on YouTube.]
Finally, the school authorities at the University of Pisa recognized his talents and appointed him as the Professor of Mathematics when he was twenty-five. Shortly after that, he felt secure enough in his position to publicly challenge the old philosophy of Aristotle. One of Aristotle's teachings said that the time a stone takes to fall depends on its weight. It seems obvious that it would have been simple to test this by dropping stones and watching them fall. But Aristotle had said it, therefore it was true and could not be questioned. Was Galileo arrogant enough to think he knew better than Aristotle? Galileo decided to prove how absurd it was to accept a doctrine simply because it had been taught for centuries. The Leaning Tower of Pisa was tall enough for his purposes. The young professor carried a large heavy object and a small lighter object to the top of the tower. Then he dropped them at the exact same time from the overhanging while a large group of people watched from below. According to Aristotle, the large heavy object should hit the ground first. But they both fell side by side and hit the ground at the same time! And so the first step had been taken to throw off the idea that principles should be accepted solely on authority without testing to see if they were actually true. That kind of thinking had impeded the growth of science knowledge for almost two thousand years.
[View a brief clip where the BBC re-enacted his experiment with a large and small tomato, and showed it being demonstrated on the moon, where there's no air resistance, with a hammer and a feather. It's on YouTube.]
This was a revolutionary attitude, and was not taken well by the University authorities. But those weren't his only enemies. Don Giovanni de Medici, the Governor of the Port of Leghorn, had designed a contraption to pump out a dock. But Galileo told him why it couldn't work -- and he told him in such an aggressive way that Don Giovanni was greatly offended. He wasn't appeased when he tried out his invention and realized that Galileo had been correct. Life was made so unpleasant for Galileo that he gave up his position at the University of Pisa. He was fortunate in having devoted friends, though -- they used their influence to get him a position as Professor of Mathematics at Padua, about 150 miles away, so he went there in 1592. [He was 28 at this time.]
It was in Padua that Galileo began the investigative work that revolutionized science. He threw himself zealously into his new job. He was soon drawing large crowds to hear his lectures about Natural Philosophy [science]. He also tutored students privately in his home who wanted special lessons. If he had any spare moments, he spent them on his own scientific research and experiments.
Galileo had a remarkable talent for inventing the tools he needed to carry out his research. In 1599, he hired a skilled workman to live with him and help him create and test the equipment he invented. One of his earliest inventions was the thermometer, which he made in 1602, though it was probably more primitive than modern thermometers. He used water instead of mercury -- as it expanded, it would measure the temperature. Then he tried alcohol, which worked a bit better. Mercury wasn't used for another fifty years [and is rarely used today because of its toxicity, but alcohol is still sometimes used].
[View a science model of how Galileo's thermometer used water density to measure temperature on YouTube.]
It was around this time that Galileo made his first telescope. This is what he wrote in a letter to his brother-in-law, Landucci:
'I'm writing because I have some news for you, although I don't know whether you'll think it's good news or bad news. I have no hope of returning home to my own region. The reason, hopefully, will result in something useful and honourable. If you remember, about two months ago there was gossip that Count Maurice of Nassau was presented with a piece of glass [a lens] manufactured in Flanders that could make objects as far away as two miles look close enough to make out the details clearly. This seemed so wonderful that I started to think about it. It seemed to be related to the theory of Perspective, so I tried to figure out how to make one of these glass pieces. Finally I figured it out, and I think what I've made is even better than the Dutch one. Someone in Venice found out I had made it, and a week later, I was summoned there to show it to the Duke and the members of his senate. They were amazed! Now many men, both gentlemen and senators, even very old men, have climbed up to the highest bell towers in Venice to catch a glimpse through my telescope of ships heading for the mouth of the harbor, and they've been able to see them clearly. Without my telescope, ships at that distance wouldn't be visible for two hours! My telescope makes objects that are fifty miles away look as if they were only five miles away.'
[Note that Galileo didn't invent the telescope, but he was the first to use one to look at the heavens. View a 4-min video about Galileo's telescope, including photographs of his actual telescopes, on YouTube.]
Intellectual men immediately recognized how useful such an instrument would be. Galileo received requests for telescopes from all over. He did make quite a few, but these were given as gifts to important and distinguished people.
Although Galileo didn't invent the first telescope, he was the one who first used it to look up at the sky and usher in a whole new era in astronomy. His first surprise was just how many stars there were up in the sky. When he looked through his little tube with its magnifying glass piece, he could see ten times as many stars as he normally could with his unaided eye. In our day, we're so familiar with the basic facts of astronomy that it's hard for us to imagine how people perceived the heavens before the telescope was invented. Galileo and everyone else who thought about such things thought that the stars were attached to the surface of a sphere that surrounded the earth, so that all the stars were the same distance from us. But seeing how many stars were out there through the lens of a telescope made it hard to believe such a thing. A person seeing this with his own eyes would have to admit that the telescope was bringing stars into view that had been impossible to see before -- just like the far-off ships in the Venice harbor that were made visible by the telescope. Those ships had been there all along, but they were too far away for the unaided eye to see.
One discovery led rapidly to another. Nobody had ever seen the nature of the Milky Way until they saw it through Galileo's magic telescope. What had looked like a cloudy area of silverish light now appeared as star-dust scattered across the black sky. It was obvious that, even though the individual stars were too small to see without some kind of device, they were there, and there were so many of them that they created a collective luminous glow that every star-gazer has admired.
But the most amazing discovery of those early days -- perhaps the most amazing discovery ever made with the telescope -- was the discovery of the four moons revolving around the planet Jupiter. It was so unexpected to Galileo that he could hardly believe his eyes. But he soon confirmed that Jupiter did, indeed, have four moons. All kinds of distinguished people came to visit Galileo and look for themselves at Jupiter, which seemed like a miniature sun with orbiting planets.
Of course, there were some people who refused to believe that there were four more moving bodies in the solar system. They scoffed at the whole idea. They said that the satellites might be inside the telescope, but it was impossible to believe that they could be in the sky. One skeptic said that even if he could see the moons of Jupiter with his own unaided eye, he still wouldn't believe in them because their existence went against common sense!
This discovery carried a troublesome significance for the prevailing worldview. In those days, Copernicus had just proposed his theory that it was the sun, and not the earth, at the center of the solar system, and the earth, rotating on its axis once a day, made a huge circle around the sun every year. This new theory had been furiously opposed. It's possible that Galileo wasn't completely convinced that Copernicus's theory was correct, but once he saw four small globes circling around Jupiter, it seemed to him to symbolize the planets orbiting the sun. In his mind, it confirmed Copernicus's theory. This change in his opinion was to have an impact on Galileo in the future.
[View NASA time-lapse images of Jupiter's four moons on YouTube. You can also see this in real time: an amateur astronomer posted some footage of each planet from his own telescope; Jupiter starts at 2:40.]
Galileo missed his beloved Tuscany. His residence in Padua felt like exile, and he longed to go back to his own country. Finally he had the opportunity. Galileo had become so famous that Tuscany's Grand Duke asked him to come and live in Florence [a city within the Tuscany region] and bring some glory to Tuscany. His offer was accepted, and Galileo was living in Florence with the title of Mathematician and Philosopher to the Grand Duke by 1616.
Two daughters, Virginia and Livia, and a son, Vincenzo, had been born while he lived in Padua. [When he moved to Florence in 1610 he brought along his two daughters, who were aged 8 and 9, but left his 4-year old son in Padua with their mother, Marina di Andrea Gamba; she died in 1612.] In those days in Italy, young women of higher ranking families were either given in marriage or became nuns. Galileo arranged for his daughters to enter the Franciscan convent of St. Matthew, at Arcetri. [Arcetri is in Florence. It's likely that Galileo placed his daughters in the convent while they were still fairly young because their mother had died. The younger brother became a lute player, like his grandfather.] Virginia, the older daughter, took her vows to become a nun in 1616 and took on the name of Sister Mary Celeste. Livia, the younger daughter, took her vows the following year, and took the name of Sister Arcangela. She was more delicate and did not adjust well to life as a nun, and very little is known about her. But the older daughter, Mary Celeste, kept up a close intimacy with her father even though she never left the convent. Once in a while Galileo visited her at the convent, but their relationship was mostly carried on through letters. These letters were frequent and affectionate, especially towards the end of his life [though she died nine years before he did]. All of the letters he wrote to her have been lost -- they may have been burned when he was captured by the Inquisition so they couldn't be used as evidence against him, or put the convent at risk. But luckily for us, all of Sister Maria Celeste's letters to her father were preserved, and they are quite touching. When we read them, we see how sweet and gentle Sister Maria Celeste was. She would probably be embarrassed to know that her letters had been published!
[Dava Sobel, who wrote the book "Galileo's Daughter," provided English translations of all 124 letters from his daughter that were found in Galileo's effects after he died. They are online here.]
Her loving notes to her "dearest lord and father" were usually accompanied with some gift, often trivial, but they were the best the destitute nun had to give. The tender affection of these letters is even more precious when we realize that the rest of Galileo's relatives were worthless. Galileo always did his duty very generously for his family, but their foolishness, bad habits, selfishness, and demands were a constant source of annoyance to him until almost the very end of his life.
In a letter from December 19, 1625, Sister Maria Celeste wrote,
'I am sending you two baked pears for these days of vigil [advent?], but I'm also sending you an even greater treat: a rose! It is so rare at this season, I'm sure you will enjoy it. This rose has thorns which represent the bitter passion of Christ, while the green leaves represent the hope we have that if we take part in that same passion, then after we have passed through the dark, winter days of our short physical life, we may reach the bright happiness of eternal springtime in heaven.'
When the wife and children of Galileo's shiftless brother ended up living with Galileo, Sister Maria Celeste wrote that she was glad because now her father had someone at home who might look after him, however imperfectly. A sweet note on Christmas Eve accompanied the little gifts she sent. She wrote,
'In these holy days, may God's peace rest on you and the entire household. The largest collar and sleeves are for Albertino; the other two are for the two younger boys. The little dog is for the baby, and the cakes are for everyone -- except the spice cakes. Those are for you. Please accept my good-will. I wish I was able to do more.'
Galileo was unbelievably patient about giving his time, his money, and his influence to help people who repeatedly proved how unworthy they were of even his notice. Sister Maria Celeste writes,
'It seems to me, dearest lord and father, that you're doing the right thing since you take every opportunity to shower continual benefits upon people who only repay you with ingratitude. Not only is your behaviour more difficult, but it's also more virtuous and good.'
Later, when the plague was in the area, his daughter's love is evident in her correspondence:
'I'm sending you two jars of supplements as a preventative against the plague. The unlabeled one has dried figs, walnuts, rue [bitter medicinal herbs], and salt, all mixed together with honey. Take a walnut-sized piece every morning before breakfast with a little bit of Greek wine.'
When the plague continued, Sister Maria Celeste worked hard to get a small quantity of a famous liqueur concocted by an exceptionally devout nun named Abess Ursula. Then she sent it to her father with this note:
'Please have faith in this remedy. If you have so much faith in my pathetic prayers, you should have even more faith in the prayers of this holy nun. With her blessing on this remedy, you should be safe from any danger of the plague.'
We don't know whether he used the remedy or not -- but we do know that he never caught the plague.
Galileo used his telescope at his new home in Florence, and made some astounding discoveries. After his surprise about Jupiter's moons, he looked next at Saturn. What he saw was equally amazing, although he didn't know how to interpret it. It was obvious that Saturn had more than a round globe like Jupiter or Mars. It looked to Galileo like it had three parts -- a large ball with a smaller ball on each side. It was so mysterious that Galileo announced this discovery in a mysterious way. He published a string of letters from the alphabet. When they were transposed correctly, they made a sentence that stated that Saturn had three parts. Now we know that what he saw was actually the two parts of Saturn's ring that stick out from the sides of the planet. But Galileo's telescope wasn't strong enough to see the detail of the rings, so it looked like two smaller masses attached to the bigger globe.
Galileo's last great astronomical discovery had to do with the moon's libration [a movement that Skywise describes like this: "it is as if the Moon is both nodding its head 'yes' and shaking its head 'no' at the same time" over the course of the month]. The very fact that he even detected this phenomenon shows, even more so than his telescope research, what an acute observer he was. We know that the moon keeps its same side facing the earth all the time. But when the position of the moon's spots and landmarks are carefully measured over time, we see that it moves slightly to the east or to the west, and to the north or to the south.
But what makes Galileo's career so interesting as a biographer isn't so much what he discovered, but what he suffered. Both are closely related [he suffered because of his discoveries], and what he went through is one intense scene in what might be considered the greatest drama in the history of science.
When Copernicus published his theory that the earth was not a stationary planet with the universe revolving around it, but was turning on its axis while it orbited the sun, orthodox church officials were appalled [because if the humanity on earth wasn't the center of the universe, then maybe mankind wasn't so important to God]. The Roman Catholic Church examined Copernicus's book, "De Revolutionibus Orbium Coelestium" [On the Revolutions of the Heavenly Spheres] in 1615, and added it to their Index of heretical books. Galileo was suspected of believing and promoting Copernicus's unacceptable apostate ideas. He was privately summoned to appear before Cardinal Bellarmine in Rome in February 1616, and ordered not to teach or defend Copernicus's heretical ideas. [Britannica.com says that Bellarmine, "somewhat sympathetic to Galileo's views, granted him an audience in which he warned him not to defend the Copernican theory but to regard it only as a hypothesis."] Galileo was dismayed at this. It would be difficult to be restricted and unable to talk freely to his friends about the Copernican system, and to have to stifle the truth about the theory that he fully believed. But he was even more saddened to think that the Church would suspect him of unbelief. He was sincerely devoted to the Church, and Cardinal Bellarmine's doubt about his faith and loyalty grieved him.
That same year, Galileo was invited to visit Pope Paul V. The pope walked with Galileo for 45 minutes. Galileo complained to his Holiness about his enemies who were trying to disgrace him before the church authorities, but the Pope told him to take comfort, that he had no doubts about the soundness of Galileo's beliefs, and that those who maintained the Index of heretical books would give him no further trouble as long as he was the Pope of St. Peter's Basilica.
Pope Paul V. died in 1623 [seven years later] and Maffeo Barberini became the new Pope, taking the name of Urban VIII. As a cardinal, Maffeo Barberini had been a close friend of Galileo's and even written a Latin poem praising Galileo and his discoveries in astronomy, so Galileo rested in the assurance that, as long as he was careful, he'd be able to continue his research and writing without fearing the Church. In fact, one of Galileo's friends sent him a note from Rome in 1624 urging him to come visit. He wrote,
'Under the influence of this excellent, educated, and kind Pope, science will certainly flourish. Your visit will be welcomed by his Holiness. He asked me if you were coming, and when you'd be here. He seems to love and value you more than ever.'
So Galileo made a trip to Rome. When he returned home to Florence, the Pope sent him home with a letter to be given to Fernando II de Medici, the Grand Duke of Tuscany [Florence is a city in the region of Tuscany, which was a state at the time]. The letter included this paragraph:
'Galileo is not only a man of literary distinction, but he is also very pious, and very strong in all the qualities that the Pope appreciates. He has just visited me in Rome to congratulate me on my position as Pope, and I have lovingly welcomed him. I cannot allow him to leave Rome and go back to your jurisdiction without a reminder of how much his Pope loves him. We gave him this note to deliver to you so that you would also be aware of how virtuous and devout he is. Whatever benefit you can do for him in imitation of your father's goodness to him -- or perhaps even more generosity than your father showed him -- will gratify me tremendously.'
The new Pope's favor made Galileo think that the church authorities would relax their attitude about the earth's position in the solar system. So he went to work preparing his greatest work, "The Dialogue of the two Systems" [which compared Ptolemy's geocentric model of the solar system with Copernicus's heliocentric theory]. When it was finished, he submitted it to the proper church authorities to be reviewed and inspected. The Pope himself thought that it would be fine with a few changes. First, the title should be carefully worded to present the Copernican system as a mere theory rather than fact. And he suggested that Galileo end the book with some special comments that the Pope had written -- arguments that the Pope thought would make it clear that he was decidedly against Copernicus's new doctrine.
Under these conditions, the Inquisitor General gave Galileo formal permission to publish his "Dialogue." But this was not the end of Galileo's troubles over his book. Niccolo Riccardi, the Master of the Sacred Palace [the pope's official theologian] suddenly had misgivings about Galileo's book. He demanded that Galileo get the manuscript from the printer's so he could examine the doctrine that was implied in the book again. He didn't feel that he had given the book enough scrutiny before the manuscript had been rushed off to the printer's. That caused the publication to be delayed. But finally, in June 1632, Galileo's great book, "The Dialogue of the two Systems,"was published for the world to read and learn from -- although it cost Galileo a lot of anxiety and danger that threatened to ruin him.
When the book was published, it was welcomed and read eagerly. But soon the Master of The Sacred Palace regretted that he had given his approval. He ordered that every copy in Italy should be confiscated. This sudden change in the Church's attitude prompted the Grand Duke of Tuscany to question the authorities in Rome. What was going on? Even the Pope himself suddenly seemed to think the book contained some kind of heresy. Even though the Church had examined the book before, they thought they had mistaken its true tendency. The Pope responded to the Duke's questions. He wrote that he was turning the book over for further review to some educated, serious, and devout men who would consider every word in it. The Pope's personal opinion was that Galileo's book was dangerous.
The church authorities reprimanded the The Master of the Sacred Palace for giving his consent to the book's publication. His excuse was that the book was supposed to be published under certain conditions but that the book had ended up being published without those conditions being met. Galileo had not inserted comments from the Pope that argued for Ptolemy's old, orthodox view. The Pope's last comment was the only one that had been included, but that actually made things worse for Galileo. He had made the Pope's comment seem to be coming from one of the characters in his book -- someone named "Simplicio." That made it seem like he was calling the Pope a simpleton. Galileo's friends said that Galileo meant no such thing. But it's very likely that this is what caused the church authorities to have a sudden change in his attitude.
In October 1632, Galileo was summoned to appear before the Inquisition in Rome to answer serious charges of heresy. Galileo was willing to answer the charges, but he asked if he could be allowed not to travel to Rome. He was an old man with failing health, and winter was coming on. But the Pope was immovable. He said he had warned Galileo of this danger when they were still friends. The command of the Church must be obeyed. Galileo could take as much time as he needed to make the journey, but he was required to leave immediately.
By now it was late January 1633 -- quite cold [Rome can have freezing temperatures and icy rains in January]. Galileo began his weary journey to Rome to obey the compulsory summons. He arrived in the middle of February and stayed with Francesco Niccolini, the Tuscan ambassador. Niccolini acted as a wise and kind friend to Galileo throughout the entire ordeal in Rome. The authorities at the church wanted Galileo to be treated with as much compassion and respect as possible, while still proceeding with the charge of heresy to the end. The Pope said that, because of his regard for the Grand Duke of Tuscany, he would bend the rules and allow Galileo to stay at the ambassador's house under house arrest instead of being locked up in a dungeon, like most prisoners of the Inquisition. When his trial actually began, he was allowed to stay in comfortable rooms at the Palace of the Holy Office.
Francesco Niccolini had instructed Galileo to use careful, appeasing language of submission with the Inquisitors. This worked so effectively that the Inquisitors recommended to the Pope that Galileo be released. As a result, he was allowed to move back into the ambassador's house for the remainder of his trial, where the ambassador heartily welcomed him. Sister Maria Celeste must have thought this meant his trial was over. She wrote,
'Your last letter brought me so much joy! I had to read it again and again to the other nuns, and they were so jubilant to hear the good news, that I got overly excited and ended up with a severe headache.'
As his defense, Galileo reminded the court that he had already been charged with heresy and acquitted in 1616 by Cardinal Bellarmine. He hadn't written anything in his book that he hadn't said then, and at that time, the authorities had said that his doctrines were fine. The Inquisition authorities were ready to be merciful, but the Pope wasn't satisfied. So Galileo had to go back for more testifying on June 21. He was threatened with torture if he didn't give a satisfactory reason explaining why he wrote his Dialogue. During all of this, the Pope assured the Tuscan ambassador that his servant Galileo was being treated with the kindest consideration because of the Pope's respect for the Duke. But Galileo had to be punished as an example. After all, by publishing his Dialogue, he had blatantly disregarded the Church's 1616 command to stop teaching Copernican theory. And it wouldn't do for Galileo for plead that his book had been approved by the Master of the Sacred College who had inspected it twice, since the Master of the Sacred College didn't know that Galileo had already been warned about this very thing sixteen years ago. Galileo should have alerted him of that fact.
On June 22, 1633, Galileo was led to the great hall where Inquisition trials were held. He was forced to kneel in front of the cardinals who were assembled there while they read his verdict and sentence. They read from a long document written up elaborately. It said that, in publishing his Dialogue, he had made the serious error of talking about Copernican's theory -- that the earth moved -- as if it was a topic that was open for discussion. The document went on to say that the Church had already denounced the Copernican theory as heresy, and by writing as if that theory might have even a shadow of probability was disrespectful towards the church and could not be overlooked. Galileo was also charged with writing as if the characters in his book who promoted the forbidden Copernican theories had better, stronger arguments than the characters who supported the orthodox, accepted doctrine.
After considering all of Galileo's explanations and defensive arguments, the Church decreed that Galileo was henceforth vehemently suspected of heresy. Therefore, he was subject to all of the harshness and penalties that the Church punished heretics with. The most serious penalties [death and torture] would be rescinded if Galileo would renounce Copernicus's theories and admit that they were heretical in a formal announcement that the Church would guide him in composing.
The Church also felt it was necessary to make an example of Galileo because of the serious offense he had committed as a warning to others. Thus, he would be imprisoned in the Holy Office for as long as the authorities thought appropriate, and he would have to recite the seven Penitential Psalms [Ps 6, 31, 37, 50, 101, 129, 142] once a week for three years.
It was a memorable scene when Galileo, aged and frail, the immortal astronomer and maker of telescopes, knelt down in front of the most eminent and reverend Lords Cardinal, Inquisitors General throughout the Catholic world, to retract and beg pardon for his depraved heresy. With his hands on the New Testament books of the Gospels, Galileo had to formally curse and detest his opinion that the sun was the center of the universe and stationary, and that the earth was not the center of the universe and that it moved. He had to vow never to write doctrines and ideas that would put him under suspicion, or else he would incur the penalty of all the pains and tortures of the Inquisition. Then his disciples and students were assembled in Florence and his retraction was read out loud in in front of them.
The reigning popes didn't sign the decrees concerning Galileo in 1616 or in 1633. To some, that means that neither Paul V. nor Urban VIII. can really be considered technically guilty of persecuting Galileo. In fact, this situation with Galileo has been referred to related to the infallibility of the Pope.
We can imagine how anxious Maria Celeste must have been about her beloved father during these terrible trials. The wife of Galileo's loyal friend, the ambassador, wrote to Sister Maria Celeste to give her whatever assurances she could to help ease her mind. Meanwhile, Maria Celeste and her father continued to correspond through letters. One of her notes said,
'Hearing about your new trouble has pierced my soul with grief -- especially because it came so unexpectedly!'
Then, when she found out he had finally been allowed to leave Rome:
'I can't tell you how much the nuns here rejoiced to hear that you arrived safely in Siena! Their happiness was wonderful. When the Mother Abbess heard the news, she and some of the other nuns ran up to me, hugging me and weeping for joy.'
The Pope was lenient about Galileo's imprisonment. Galileo was allowed to live under house arrest at the archbishop's house in Siena. The worst part of being confined there was the separation from his daughter, whom he had come to love dearly. She had often told him that she was never happier than when she could do some service for her father. She was overjoyed to find out that there was something she could do to help him: she could relieve him of the task of reciting the seven Penitential Psalms as part of his penance. She writes,
'I started doing this for you a while ago, and it gives me so much joy. First, because praying these Psalms out of obedience to the church can only be a blessing, and second, because it saves you the trouble of having to remember to do it. I wish I could do more for you. I would have been willing to go to prison myself if it could have set you free.'
Sister Maria Celeste's health started to decline, and she was allowed to visit and embrace her father. Then Galileo was finally permitted to go back to his own home. On the very day he learned that his daughter had died [1634], he also learned about the decree commanding that he must remain under house arrest in solitary confinement in his home.
Galileo was getting old. He was isolated from his friends and grieving over his daughter's death. Once again, he sought consolation in his work. He went to work on his book "De Motu" [On Motion]. Then his sight began to fail, and he had to deal with blindness on top of all his other sorrows. In January, 1638, he wrote to his lawyer friend Elie Diodati--
'I'm sorry to say that for the last month, I've been completely blind. The heavens, the earth, the entire universe that my discoveries have enlarged for the whole world, have become for me no larger than the space I can perceive by touch.'
Galileo, the great philosopher, died of a fever in January, 1642 at the age of 77.
by Sir Robert S. Ball, 1895 (paraphrased by Leslie Noelani Laurio)
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Galileo Galilei. 1564-1642
Not only the first astronomer to use the telescope; he paved the way for the acceptance of Copernicus's heliocentric model of the universe.
Of all the famed astronomers, it would be hard to find one whose life had more interesting events and fluctuations than Galileo's. He was a patient investigator and a brilliant discoverer. He had some fascinating personal relationships, especially with his daughter, Sister Maria Celeste, who was a very exceptional woman. There was also the sad drama near the end of his life, when his work drew the criticism of the Inquisition.
There are many resources about Galileo's life to use for writing a biography. This chapter made use of the charming letters his daughter wrote to him from her convent. More than a hundred of them survived, and they are extraordinarily beautiful and touching and show how much his daughter loved him. There's also a collection called "The Private Life of Galileo," published by Macmillan in 1870; some facts for this chapter have come from that book. [The book is mostly his correspondence with his daughter; it is online at archive.org.]
Galileo was born at Pisa [Italy] on February 18, 1564. He was the oldest son of Vincenzo de Bonajuti de Galilei, a Florentine noble. Even so, the family lived in poverty and Galileo knew that he would need to learn some kind of profession to support himself. He inherited a love for music from his father, who was an excellent lute player. He also had some artistic ability, and entertained the idea of a career as a painter. But his father decided he should study medicine. So, at the age of seventeen, with a knowledge of Greek and Latin as well as art, he was enrolled at the University of Pisa.
It was here at the University of Pisa that Galileo gained some understanding of mathematics. He found math so interesting that he begged to be allowed to study geometry, so his father reluctantly let him hire a math tutor. He was concerned that Galileo might be distracted from his medical studies, and his concerns weren't unfounded. Euclid's book of geometry propositions engrossed Galileo so much that his father decided to let the tutor go so his son could put his mind back on his medical lessons. But now it was too late. Galileo had caught on so quickly that he no longer needed a tutor; he was able to study geometry on his own. Soon he had grasped Euclid's 47th proposition ["In right-angled triangles the square on the side opposite the right angle equals the sum of the squares on the sides containing the right angle;" read more here] and he kept going until he had mastered all six books of Euclid -- a considerable feat in those days. [And in these days, too!]
But his diligence and brilliance didn't win him much approval with the Pisa University authorities. Back then, Aristotle's ideas were considered the epitome of human wisdom in natural science and everything else. It was considered the duty of every scholar to learn Aristotle by heart. Any student who dared to doubt or even question Aristotle's doctrines was considered extremely arrogant. But young Galileo was bold and reckless enough to think through his own ideas about how nature worked. He wouldn't blindly accept anyone else's principles until he could test them himself to see if they were true. His teachers started to think of him as a misguided young fool, even though they couldn't help respecting his energy and diligence as he collected all the knowledge he could find.
We are so accustomed to pendulums in clocks that we forget it was Galileo who invented them. He was sitting in the Cathedral at Pisa one day and his attention was drawn to a chandelier swinging from the ceiling. He noticed that whether the chandelier made a wide arc or a short one, the time it took to get from one side to the other was the same. To his observant mind, that made it useful for marking time. So Galileo constructed the first timepiece controlled by pendulum motion. He intended it as a tool for doctors to measure the pulse rates of their patients. [View a replica on YouTube.]
Finally, the school authorities at the University of Pisa recognized his talents and appointed him as the Professor of Mathematics when he was twenty-five. Shortly after that, he felt secure enough in his position to publicly challenge the old philosophy of Aristotle. One of Aristotle's teachings said that the time a stone takes to fall depends on its weight. It seems obvious that it would have been simple to test this by dropping stones and watching them fall. But Aristotle had said it, therefore it was true and could not be questioned. Was Galileo arrogant enough to think he knew better than Aristotle? Galileo decided to prove how absurd it was to accept a doctrine simply because it had been taught for centuries. The Leaning Tower of Pisa was tall enough for his purposes. The young professor carried a large heavy object and a small lighter object to the top of the tower. Then he dropped them at the exact same time from the overhanging while a large group of people watched from below. According to Aristotle, the large heavy object should hit the ground first. But they both fell side by side and hit the ground at the same time! And so the first step had been taken to throw off the idea that principles should be accepted solely on authority without testing to see if they were actually true. That kind of thinking had impeded the growth of science knowledge for almost two thousand years.
[View a brief clip where the BBC re-enacted his experiment with a large and small tomato, and showed it being demonstrated on the moon, where there's no air resistance, with a hammer and a feather. It's on YouTube.]
This was a revolutionary attitude, and was not taken well by the University authorities. But those weren't his only enemies. Don Giovanni de Medici, the Governor of the Port of Leghorn, had designed a contraption to pump out a dock. But Galileo told him why it couldn't work -- and he told him in such an aggressive way that Don Giovanni was greatly offended. He wasn't appeased when he tried out his invention and realized that Galileo had been correct. Life was made so unpleasant for Galileo that he gave up his position at the University of Pisa. He was fortunate in having devoted friends, though -- they used their influence to get him a position as Professor of Mathematics at Padua, about 150 miles away, so he went there in 1592. [He was 28 at this time.]
It was in Padua that Galileo began the investigative work that revolutionized science. He threw himself zealously into his new job. He was soon drawing large crowds to hear his lectures about Natural Philosophy [science]. He also tutored students privately in his home who wanted special lessons. If he had any spare moments, he spent them on his own scientific research and experiments.
Galileo had a remarkable talent for inventing the tools he needed to carry out his research. In 1599, he hired a skilled workman to live with him and help him create and test the equipment he invented. One of his earliest inventions was the thermometer, which he made in 1602, though it was probably more primitive than modern thermometers. He used water instead of mercury -- as it expanded, it would measure the temperature. Then he tried alcohol, which worked a bit better. Mercury wasn't used for another fifty years [and is rarely used today because of its toxicity, but alcohol is still sometimes used].
[View a science model of how Galileo's thermometer used water density to measure temperature on YouTube.]
It was around this time that Galileo made his first telescope. This is what he wrote in a letter to his brother-in-law, Landucci:
'I'm writing because I have some news for you, although I don't know whether you'll think it's good news or bad news. I have no hope of returning home to my own region. The reason, hopefully, will result in something useful and honourable. If you remember, about two months ago there was gossip that Count Maurice of Nassau was presented with a piece of glass [a lens] manufactured in Flanders that could make objects as far away as two miles look close enough to make out the details clearly. This seemed so wonderful that I started to think about it. It seemed to be related to the theory of Perspective, so I tried to figure out how to make one of these glass pieces. Finally I figured it out, and I think what I've made is even better than the Dutch one. Someone in Venice found out I had made it, and a week later, I was summoned there to show it to the Duke and the members of his senate. They were amazed! Now many men, both gentlemen and senators, even very old men, have climbed up to the highest bell towers in Venice to catch a glimpse through my telescope of ships heading for the mouth of the harbor, and they've been able to see them clearly. Without my telescope, ships at that distance wouldn't be visible for two hours! My telescope makes objects that are fifty miles away look as if they were only five miles away.'
[Note that Galileo didn't invent the telescope, but he was the first to use one to look at the heavens. View a 4-min video about Galileo's telescope, including photographs of his actual telescopes, on YouTube.]
Intellectual men immediately recognized how useful such an instrument would be. Galileo received requests for telescopes from all over. He did make quite a few, but these were given as gifts to important and distinguished people.
Although Galileo didn't invent the first telescope, he was the one who first used it to look up at the sky and usher in a whole new era in astronomy. His first surprise was just how many stars there were up in the sky. When he looked through his little tube with its magnifying glass piece, he could see ten times as many stars as he normally could with his unaided eye. In our day, we're so familiar with the basic facts of astronomy that it's hard for us to imagine how people perceived the heavens before the telescope was invented. Galileo and everyone else who thought about such things thought that the stars were attached to the surface of a sphere that surrounded the earth, so that all the stars were the same distance from us. But seeing how many stars were out there through the lens of a telescope made it hard to believe such a thing. A person seeing this with his own eyes would have to admit that the telescope was bringing stars into view that had been impossible to see before -- just like the far-off ships in the Venice harbor that were made visible by the telescope. Those ships had been there all along, but they were too far away for the unaided eye to see.
One discovery led rapidly to another. Nobody had ever seen the nature of the Milky Way until they saw it through Galileo's magic telescope. What had looked like a cloudy area of silverish light now appeared as star-dust scattered across the black sky. It was obvious that, even though the individual stars were too small to see without some kind of device, they were there, and there were so many of them that they created a collective luminous glow that every star-gazer has admired.
But the most amazing discovery of those early days -- perhaps the most amazing discovery ever made with the telescope -- was the discovery of the four moons revolving around the planet Jupiter. It was so unexpected to Galileo that he could hardly believe his eyes. But he soon confirmed that Jupiter did, indeed, have four moons. All kinds of distinguished people came to visit Galileo and look for themselves at Jupiter, which seemed like a miniature sun with orbiting planets.
Of course, there were some people who refused to believe that there were four more moving bodies in the solar system. They scoffed at the whole idea. They said that the satellites might be inside the telescope, but it was impossible to believe that they could be in the sky. One skeptic said that even if he could see the moons of Jupiter with his own unaided eye, he still wouldn't believe in them because their existence went against common sense!
This discovery carried a troublesome significance for the prevailing worldview. In those days, Copernicus had just proposed his theory that it was the sun, and not the earth, at the center of the solar system, and the earth, rotating on its axis once a day, made a huge circle around the sun every year. This new theory had been furiously opposed. It's possible that Galileo wasn't completely convinced that Copernicus's theory was correct, but once he saw four small globes circling around Jupiter, it seemed to him to symbolize the planets orbiting the sun. In his mind, it confirmed Copernicus's theory. This change in his opinion was to have an impact on Galileo in the future.
[View NASA time-lapse images of Jupiter's four moons on YouTube. You can also see this in real time: an amateur astronomer posted some footage of each planet from his own telescope; Jupiter starts at 2:40.]
Galileo missed his beloved Tuscany. His residence in Padua felt like exile, and he longed to go back to his own country. Finally he had the opportunity. Galileo had become so famous that Tuscany's Grand Duke asked him to come and live in Florence [a city within the Tuscany region] and bring some glory to Tuscany. His offer was accepted, and Galileo was living in Florence with the title of Mathematician and Philosopher to the Grand Duke by 1616.
Two daughters, Virginia and Livia, and a son, Vincenzo, had been born while he lived in Padua. [When he moved to Florence in 1610 he brought along his two daughters, who were aged 8 and 9, but left his 4-year old son in Padua with their mother, Marina di Andrea Gamba; she died in 1612.] In those days in Italy, young women of higher ranking families were either given in marriage or became nuns. Galileo arranged for his daughters to enter the Franciscan convent of St. Matthew, at Arcetri. [Arcetri is in Florence. It's likely that Galileo placed his daughters in the convent while they were still fairly young because their mother had died. The younger brother became a lute player, like his grandfather.] Virginia, the older daughter, took her vows to become a nun in 1616 and took on the name of Sister Mary Celeste. Livia, the younger daughter, took her vows the following year, and took the name of Sister Arcangela. She was more delicate and did not adjust well to life as a nun, and very little is known about her. But the older daughter, Mary Celeste, kept up a close intimacy with her father even though she never left the convent. Once in a while Galileo visited her at the convent, but their relationship was mostly carried on through letters. These letters were frequent and affectionate, especially towards the end of his life [though she died nine years before he did]. All of the letters he wrote to her have been lost -- they may have been burned when he was captured by the Inquisition so they couldn't be used as evidence against him, or put the convent at risk. But luckily for us, all of Sister Maria Celeste's letters to her father were preserved, and they are quite touching. When we read them, we see how sweet and gentle Sister Maria Celeste was. She would probably be embarrassed to know that her letters had been published!
[Dava Sobel, who wrote the book "Galileo's Daughter," provided English translations of all 124 letters from his daughter that were found in Galileo's effects after he died. They are online here.]
Her loving notes to her "dearest lord and father" were usually accompanied with some gift, often trivial, but they were the best the destitute nun had to give. The tender affection of these letters is even more precious when we realize that the rest of Galileo's relatives were worthless. Galileo always did his duty very generously for his family, but their foolishness, bad habits, selfishness, and demands were a constant source of annoyance to him until almost the very end of his life.
In a letter from December 19, 1625, Sister Maria Celeste wrote,
'I am sending you two baked pears for these days of vigil [advent?], but I'm also sending you an even greater treat: a rose! It is so rare at this season, I'm sure you will enjoy it. This rose has thorns which represent the bitter passion of Christ, while the green leaves represent the hope we have that if we take part in that same passion, then after we have passed through the dark, winter days of our short physical life, we may reach the bright happiness of eternal springtime in heaven.'
When the wife and children of Galileo's shiftless brother ended up living with Galileo, Sister Maria Celeste wrote that she was glad because now her father had someone at home who might look after him, however imperfectly. A sweet note on Christmas Eve accompanied the little gifts she sent. She wrote,
'In these holy days, may God's peace rest on you and the entire household. The largest collar and sleeves are for Albertino; the other two are for the two younger boys. The little dog is for the baby, and the cakes are for everyone -- except the spice cakes. Those are for you. Please accept my good-will. I wish I was able to do more.'
Galileo was unbelievably patient about giving his time, his money, and his influence to help people who repeatedly proved how unworthy they were of even his notice. Sister Maria Celeste writes,
'It seems to me, dearest lord and father, that you're doing the right thing since you take every opportunity to shower continual benefits upon people who only repay you with ingratitude. Not only is your behaviour more difficult, but it's also more virtuous and good.'
Later, when the plague was in the area, his daughter's love is evident in her correspondence:
'I'm sending you two jars of supplements as a preventative against the plague. The unlabeled one has dried figs, walnuts, rue [bitter medicinal herbs], and salt, all mixed together with honey. Take a walnut-sized piece every morning before breakfast with a little bit of Greek wine.'
When the plague continued, Sister Maria Celeste worked hard to get a small quantity of a famous liqueur concocted by an exceptionally devout nun named Abess Ursula. Then she sent it to her father with this note:
'Please have faith in this remedy. If you have so much faith in my pathetic prayers, you should have even more faith in the prayers of this holy nun. With her blessing on this remedy, you should be safe from any danger of the plague.'
We don't know whether he used the remedy or not -- but we do know that he never caught the plague.
Galileo used his telescope at his new home in Florence, and made some astounding discoveries. After his surprise about Jupiter's moons, he looked next at Saturn. What he saw was equally amazing, although he didn't know how to interpret it. It was obvious that Saturn had more than a round globe like Jupiter or Mars. It looked to Galileo like it had three parts -- a large ball with a smaller ball on each side. It was so mysterious that Galileo announced this discovery in a mysterious way. He published a string of letters from the alphabet. When they were transposed correctly, they made a sentence that stated that Saturn had three parts. Now we know that what he saw was actually the two parts of Saturn's ring that stick out from the sides of the planet. But Galileo's telescope wasn't strong enough to see the detail of the rings, so it looked like two smaller masses attached to the bigger globe.
Galileo's last great astronomical discovery had to do with the moon's libration [a movement that Skywise describes like this: "it is as if the Moon is both nodding its head 'yes' and shaking its head 'no' at the same time" over the course of the month]. The very fact that he even detected this phenomenon shows, even more so than his telescope research, what an acute observer he was. We know that the moon keeps its same side facing the earth all the time. But when the position of the moon's spots and landmarks are carefully measured over time, we see that it moves slightly to the east or to the west, and to the north or to the south.
But what makes Galileo's career so interesting as a biographer isn't so much what he discovered, but what he suffered. Both are closely related [he suffered because of his discoveries], and what he went through is one intense scene in what might be considered the greatest drama in the history of science.
When Copernicus published his theory that the earth was not a stationary planet with the universe revolving around it, but was turning on its axis while it orbited the sun, orthodox church officials were appalled [because if the humanity on earth wasn't the center of the universe, then maybe mankind wasn't so important to God]. The Roman Catholic Church examined Copernicus's book, "De Revolutionibus Orbium Coelestium" [On the Revolutions of the Heavenly Spheres] in 1615, and added it to their Index of heretical books. Galileo was suspected of believing and promoting Copernicus's unacceptable apostate ideas. He was privately summoned to appear before Cardinal Bellarmine in Rome in February 1616, and ordered not to teach or defend Copernicus's heretical ideas. [Britannica.com says that Bellarmine, "somewhat sympathetic to Galileo's views, granted him an audience in which he warned him not to defend the Copernican theory but to regard it only as a hypothesis."] Galileo was dismayed at this. It would be difficult to be restricted and unable to talk freely to his friends about the Copernican system, and to have to stifle the truth about the theory that he fully believed. But he was even more saddened to think that the Church would suspect him of unbelief. He was sincerely devoted to the Church, and Cardinal Bellarmine's doubt about his faith and loyalty grieved him.
That same year, Galileo was invited to visit Pope Paul V. The pope walked with Galileo for 45 minutes. Galileo complained to his Holiness about his enemies who were trying to disgrace him before the church authorities, but the Pope told him to take comfort, that he had no doubts about the soundness of Galileo's beliefs, and that those who maintained the Index of heretical books would give him no further trouble as long as he was the Pope of St. Peter's Basilica.
Pope Paul V. died in 1623 [seven years later] and Maffeo Barberini became the new Pope, taking the name of Urban VIII. As a cardinal, Maffeo Barberini had been a close friend of Galileo's and even written a Latin poem praising Galileo and his discoveries in astronomy, so Galileo rested in the assurance that, as long as he was careful, he'd be able to continue his research and writing without fearing the Church. In fact, one of Galileo's friends sent him a note from Rome in 1624 urging him to come visit. He wrote,
'Under the influence of this excellent, educated, and kind Pope, science will certainly flourish. Your visit will be welcomed by his Holiness. He asked me if you were coming, and when you'd be here. He seems to love and value you more than ever.'
So Galileo made a trip to Rome. When he returned home to Florence, the Pope sent him home with a letter to be given to Fernando II de Medici, the Grand Duke of Tuscany [Florence is a city in the region of Tuscany, which was a state at the time]. The letter included this paragraph:
'Galileo is not only a man of literary distinction, but he is also very pious, and very strong in all the qualities that the Pope appreciates. He has just visited me in Rome to congratulate me on my position as Pope, and I have lovingly welcomed him. I cannot allow him to leave Rome and go back to your jurisdiction without a reminder of how much his Pope loves him. We gave him this note to deliver to you so that you would also be aware of how virtuous and devout he is. Whatever benefit you can do for him in imitation of your father's goodness to him -- or perhaps even more generosity than your father showed him -- will gratify me tremendously.'
The new Pope's favor made Galileo think that the church authorities would relax their attitude about the earth's position in the solar system. So he went to work preparing his greatest work, "The Dialogue of the two Systems" [which compared Ptolemy's geocentric model of the solar system with Copernicus's heliocentric theory]. When it was finished, he submitted it to the proper church authorities to be reviewed and inspected. The Pope himself thought that it would be fine with a few changes. First, the title should be carefully worded to present the Copernican system as a mere theory rather than fact. And he suggested that Galileo end the book with some special comments that the Pope had written -- arguments that the Pope thought would make it clear that he was decidedly against Copernicus's new doctrine.
Under these conditions, the Inquisitor General gave Galileo formal permission to publish his "Dialogue." But this was not the end of Galileo's troubles over his book. Niccolo Riccardi, the Master of the Sacred Palace [the pope's official theologian] suddenly had misgivings about Galileo's book. He demanded that Galileo get the manuscript from the printer's so he could examine the doctrine that was implied in the book again. He didn't feel that he had given the book enough scrutiny before the manuscript had been rushed off to the printer's. That caused the publication to be delayed. But finally, in June 1632, Galileo's great book, "The Dialogue of the two Systems,"was published for the world to read and learn from -- although it cost Galileo a lot of anxiety and danger that threatened to ruin him.
When the book was published, it was welcomed and read eagerly. But soon the Master of The Sacred Palace regretted that he had given his approval. He ordered that every copy in Italy should be confiscated. This sudden change in the Church's attitude prompted the Grand Duke of Tuscany to question the authorities in Rome. What was going on? Even the Pope himself suddenly seemed to think the book contained some kind of heresy. Even though the Church had examined the book before, they thought they had mistaken its true tendency. The Pope responded to the Duke's questions. He wrote that he was turning the book over for further review to some educated, serious, and devout men who would consider every word in it. The Pope's personal opinion was that Galileo's book was dangerous.
The church authorities reprimanded the The Master of the Sacred Palace for giving his consent to the book's publication. His excuse was that the book was supposed to be published under certain conditions but that the book had ended up being published without those conditions being met. Galileo had not inserted comments from the Pope that argued for Ptolemy's old, orthodox view. The Pope's last comment was the only one that had been included, but that actually made things worse for Galileo. He had made the Pope's comment seem to be coming from one of the characters in his book -- someone named "Simplicio." That made it seem like he was calling the Pope a simpleton. Galileo's friends said that Galileo meant no such thing. But it's very likely that this is what caused the church authorities to have a sudden change in his attitude.
In October 1632, Galileo was summoned to appear before the Inquisition in Rome to answer serious charges of heresy. Galileo was willing to answer the charges, but he asked if he could be allowed not to travel to Rome. He was an old man with failing health, and winter was coming on. But the Pope was immovable. He said he had warned Galileo of this danger when they were still friends. The command of the Church must be obeyed. Galileo could take as much time as he needed to make the journey, but he was required to leave immediately.
By now it was late January 1633 -- quite cold [Rome can have freezing temperatures and icy rains in January]. Galileo began his weary journey to Rome to obey the compulsory summons. He arrived in the middle of February and stayed with Francesco Niccolini, the Tuscan ambassador. Niccolini acted as a wise and kind friend to Galileo throughout the entire ordeal in Rome. The authorities at the church wanted Galileo to be treated with as much compassion and respect as possible, while still proceeding with the charge of heresy to the end. The Pope said that, because of his regard for the Grand Duke of Tuscany, he would bend the rules and allow Galileo to stay at the ambassador's house under house arrest instead of being locked up in a dungeon, like most prisoners of the Inquisition. When his trial actually began, he was allowed to stay in comfortable rooms at the Palace of the Holy Office.
Francesco Niccolini had instructed Galileo to use careful, appeasing language of submission with the Inquisitors. This worked so effectively that the Inquisitors recommended to the Pope that Galileo be released. As a result, he was allowed to move back into the ambassador's house for the remainder of his trial, where the ambassador heartily welcomed him. Sister Maria Celeste must have thought this meant his trial was over. She wrote,
'Your last letter brought me so much joy! I had to read it again and again to the other nuns, and they were so jubilant to hear the good news, that I got overly excited and ended up with a severe headache.'
As his defense, Galileo reminded the court that he had already been charged with heresy and acquitted in 1616 by Cardinal Bellarmine. He hadn't written anything in his book that he hadn't said then, and at that time, the authorities had said that his doctrines were fine. The Inquisition authorities were ready to be merciful, but the Pope wasn't satisfied. So Galileo had to go back for more testifying on June 21. He was threatened with torture if he didn't give a satisfactory reason explaining why he wrote his Dialogue. During all of this, the Pope assured the Tuscan ambassador that his servant Galileo was being treated with the kindest consideration because of the Pope's respect for the Duke. But Galileo had to be punished as an example. After all, by publishing his Dialogue, he had blatantly disregarded the Church's 1616 command to stop teaching Copernican theory. And it wouldn't do for Galileo for plead that his book had been approved by the Master of the Sacred College who had inspected it twice, since the Master of the Sacred College didn't know that Galileo had already been warned about this very thing sixteen years ago. Galileo should have alerted him of that fact.
On June 22, 1633, Galileo was led to the great hall where Inquisition trials were held. He was forced to kneel in front of the cardinals who were assembled there while they read his verdict and sentence. They read from a long document written up elaborately. It said that, in publishing his Dialogue, he had made the serious error of talking about Copernican's theory -- that the earth moved -- as if it was a topic that was open for discussion. The document went on to say that the Church had already denounced the Copernican theory as heresy, and by writing as if that theory might have even a shadow of probability was disrespectful towards the church and could not be overlooked. Galileo was also charged with writing as if the characters in his book who promoted the forbidden Copernican theories had better, stronger arguments than the characters who supported the orthodox, accepted doctrine.
After considering all of Galileo's explanations and defensive arguments, the Church decreed that Galileo was henceforth vehemently suspected of heresy. Therefore, he was subject to all of the harshness and penalties that the Church punished heretics with. The most serious penalties [death and torture] would be rescinded if Galileo would renounce Copernicus's theories and admit that they were heretical in a formal announcement that the Church would guide him in composing.
The Church also felt it was necessary to make an example of Galileo because of the serious offense he had committed as a warning to others. Thus, he would be imprisoned in the Holy Office for as long as the authorities thought appropriate, and he would have to recite the seven Penitential Psalms [Ps 6, 31, 37, 50, 101, 129, 142] once a week for three years.
It was a memorable scene when Galileo, aged and frail, the immortal astronomer and maker of telescopes, knelt down in front of the most eminent and reverend Lords Cardinal, Inquisitors General throughout the Catholic world, to retract and beg pardon for his depraved heresy. With his hands on the New Testament books of the Gospels, Galileo had to formally curse and detest his opinion that the sun was the center of the universe and stationary, and that the earth was not the center of the universe and that it moved. He had to vow never to write doctrines and ideas that would put him under suspicion, or else he would incur the penalty of all the pains and tortures of the Inquisition. Then his disciples and students were assembled in Florence and his retraction was read out loud in in front of them.
The reigning popes didn't sign the decrees concerning Galileo in 1616 or in 1633. To some, that means that neither Paul V. nor Urban VIII. can really be considered technically guilty of persecuting Galileo. In fact, this situation with Galileo has been referred to related to the infallibility of the Pope.
We can imagine how anxious Maria Celeste must have been about her beloved father during these terrible trials. The wife of Galileo's loyal friend, the ambassador, wrote to Sister Maria Celeste to give her whatever assurances she could to help ease her mind. Meanwhile, Maria Celeste and her father continued to correspond through letters. One of her notes said,
'Hearing about your new trouble has pierced my soul with grief -- especially because it came so unexpectedly!'
Then, when she found out he had finally been allowed to leave Rome:
'I can't tell you how much the nuns here rejoiced to hear that you arrived safely in Siena! Their happiness was wonderful. When the Mother Abbess heard the news, she and some of the other nuns ran up to me, hugging me and weeping for joy.'
The Pope was lenient about Galileo's imprisonment. Galileo was allowed to live under house arrest at the archbishop's house in Siena. The worst part of being confined there was the separation from his daughter, whom he had come to love dearly. She had often told him that she was never happier than when she could do some service for her father. She was overjoyed to find out that there was something she could do to help him: she could relieve him of the task of reciting the seven Penitential Psalms as part of his penance. She writes,
'I started doing this for you a while ago, and it gives me so much joy. First, because praying these Psalms out of obedience to the church can only be a blessing, and second, because it saves you the trouble of having to remember to do it. I wish I could do more for you. I would have been willing to go to prison myself if it could have set you free.'
Sister Maria Celeste's health started to decline, and she was allowed to visit and embrace her father. Then Galileo was finally permitted to go back to his own home. On the very day he learned that his daughter had died [1634], he also learned about the decree commanding that he must remain under house arrest in solitary confinement in his home.
Galileo was getting old. He was isolated from his friends and grieving over his daughter's death. Once again, he sought consolation in his work. He went to work on his book "De Motu" [On Motion]. Then his sight began to fail, and he had to deal with blindness on top of all his other sorrows. In January, 1638, he wrote to his lawyer friend Elie Diodati--
'I'm sorry to say that for the last month, I've been completely blind. The heavens, the earth, the entire universe that my discoveries have enlarged for the whole world, have become for me no larger than the space I can perceive by touch.'
Galileo, the great philosopher, died of a fever in January, 1642 at the age of 77.
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