Summary
Scene 3. January 10, 1610. "Using the telescope, Galileo discovers celestial phenomena that confirm the Copernican system. Warned by his friend of the possible consequences of his research, Galileo proclaims his belief in human reason."
Galileo and Sagredo are at the telescope in his study. Sagredo notes the physical properties of the moon, and Galileo tells him that there are giant mountains on the surface of the moon. "But this goes against 2,000 years of astronomy," Sagredo protests, to which Galileo replies, "What you are seeing has been seen by no mortal except myself." He tells Sagredo that both the earth and the moon give off light from the sun.
When Sagredo infers that Galileo is suggesting that there is no difference between the earth and the moon, he warns him that 10 years ago, they burned a man at the stake for saying the same thing, a man named Giordano Bruno. "Today mankind can write in its diary: Got rid of Heaven," Galileo says, when suddenly the friends are interrupted by the entrance of the procurator.
The procurator tells Galileo that the telescope is useless and that he ought to throw it out, because it was already invented in Holland. Sagredo counters that Galileo has made some "revolutionary discoveries about the universe" using the telescope. The procurator only wants to talk about the commercial value of the telescope, even though Sagredo and Galileo insist that it can be used to transform the fields of science and philosophy.
Galileo explains to the procurator that he knows how to make the telescope into a profitable commodity. "I have reason to believe that the telescope will allow us to make clear sightings of certain stars that execute extremely regular movements," he says, suggesting that it could help make shipping routes more efficient. The procurator does not want to hear it, accuses Galileo of embarrassing him, and leaves, slamming the door.
Sagredo asks Galileo if he had heard about the telescopes and Galileo tells him he had, but that he made his much better. Galileo laments the fact that he needs money, that he needs a dowry for Virginia, his daughter. He also mentions that he has debts from 20 years prior. "Give me five years off to research, and I'd have proved it all," he says.
The men discuss the fact that the Milky Way is made up of stars, and Galileo shows Sagredo Jupiter and its moon, determined to figure out its movement patterns. Galileo notes that Jupiter has stars that move around it, and gets very excited, calling down to Andrea. Trying to calm down his friend, Sagredo asks Galileo, "Where is God?"
Galileo does not see this as relevant, claiming that he has proof of the physical nature of the universe, and that God cannot enter into it, that God is "within ourselves or nowhere." Sagredo tries to dissuade him from his confident theorizing, but Galileo is determined that "the lure of a proof is too great. Nearly everyone succumbs to it; sooner or later we all do. Thinking is one of the chief pleasures of the human race."
Just then, Mrs. Sarti comes in and Galileo asks her to bring him Andrea. When she tells him Andrea is asleep, Galileo tells her to wake him, that he's discovered something that will interest Andrea. With this news, Galileo asks Mrs. Sarti if the smaller goes round the greater, or the other way around. She makes a joke about the fact that she serves him his dinner, since he is "the one who has studied and is able to pay."
When she leaves, amused, Galileo turns to Sagredo and says, "Don't tell me people like that can't grasp the truth. They grab at it." Suddenly, the bell rings for morning Mass and Virginia comes in. She asks to look through the telescope, but Galileo tells her it's not a toy, before telling her that they will likely be moving to Florence soon, as he's applied to become the court mathematician for the Grand Duke.
After Virginia leaves, Galileo shows Sagredo his letter to the Grand Duke and asks him if it's well written. Sagredo reads aloud, "My most ardent desire is to be closer to you, the rising sun that will illuminate this age," before noting, "The grand duke of Florence is aged nine." Sagredo advises Galileo not to go to Florence, as "it's run by monks." Galileo insists that "the Florentine Court includes eminent scholars," and is confident that if he takes monks and others to the telescope to see his discoveries, they will have no choice but to believe him. "I'm going to take them by the scruff of the neck and force them to look through this telescope," he says.
Sagredo is worried for his friend, advising him, "It is a disastrous night when mankind sees the truth. And a delusive hour when it believes in human reason." Sagredo is sure that people will not take kindly to Galileo's insistence that heaven does not exist. "I am fond of science, my friend, but I am fonder of you," he says, but Galileo does not care and plans to go.
A curtain appears which has the last page of Galileo's letter written on it, which reads, "In giving the noble name of the house of Medici to the new stars which I have discovered I realise that whereas the old gods and heroes were immortalised by being raised to the realm of the stars in this case the noble name of Medici will ensure that these stars are remembered for ever."
Scene 4. "Galileo has exchanged the Venetian Republic for the Court of Florence. His discoveries with the telescope are not believed by the court scholars."
At Galileo's house in Florence, Mrs. Sarti and Andrea are tidying up his study for the arrival of guests. Sarti talks about the fact that she loves Florence, but that Galileo is being foolish about the gentlemen coming that night to inspect the telescope. In the middle of her monologue, the Grand Duke arrives, even though Galileo is still at the University. Cosimo de Medici, with several attendants, enters the house and requests to see the tube.
Cosimo runs up to the study where he finds Andrea, and asks what different instruments are. Andrea tells Cosimo that the earth turns around the sun. When Cosimo picks up the model, Andrea asks him to give it back and the boys get in a fight. Downstairs, Galileo comes in, and the chamberlain tells him that the court is "eager to know what our distinguished university thinks about Mr. Galileo's remarkable instrument and these amazing new stars."
Galileo and the others go upstairs, where they discover that the Ptolemaic model is broken. Galileo tells the group his theory that the old model for thinking about the universe is inaccurate. The mathematician, theologian, and philosopher assembled do not believe him, insisting that Aristotle's model of the universe is so pleasing "that we should think twice before disrupting its harmony."
Disappointed, Galileo becomes insistent that they look through the telescope to see for themselves, but the mathematician and the others suggest that "what is in your tube and what is in the skies is not necessarily the same thing." They accuse Galileo of painting the Medicean stars onto the lens, but Galileo remains insistent that they look through the telescope themselves.
Andrea storms out of the room, telling Mrs. Sarti, "They're stupid," before running off. The scholars confront Galileo, telling him they subscribe to Aristotle's vision of the universe, but Galileo protests that they are ignoring tangible facts. Federzoni, the man who helped Galileo construct the telescope, tells the scholars that they ought to be more invested in innovative discoveries. As the court gets ready to leave, Sarti tries to offer them some biscuits, but they leave. "All you gentlemen need do is look through the telescope!" Galileo yells, but they leave without doing so.
Scene 5. "Undeterred even by the plague, Galileo carries on with his researches." As Galileo looks at the telescope, Virginia comes in and tells him she's been sent home from the convent due to an outbreak of the plague. A footman enters and informs them that the Grand Duke has fled to Bologna, and that he has sent a carriage to bring them to safety. Mrs. Sarti sends Virginia and Andrea to the carriage as Galileo gathers his things. Virginia, fearing that Galileo will not come if he has to pack up all his books, tells Mrs. Sarti to help him.
Abruptly, Galileo tells Mrs. Sarti that he thinks he should stay and review his notes. "Anyway this plague is all over the place," he says. Virginia and Andrea go to Bologna, but Mrs. Sarti stays behind to cook for Galileo.
Analysis
In Sagredo, Galileo has a friend in whom he can confide about the giant astronomical discoveries he is making. He shows his friend what he sees on the moon, the mountains and the topographical oddities that could change the course of science forever. Sagredo is a trusted friend who knows both the brilliance of Galileo's discoveries, as well as their dangers and the threat they pose to his safety in the city, since they go against the religious precepts upon which the power structures in Italy are based.
The play shows explicitly the ways that Galileo's work sought to integrate the study of mathematics with philosophy. The fact that Galileo disproves the existence of the heavens subverts the entire Judeo-Christian belief system. By understanding the physical properties of the universe, Galileo can make a case for the fact that many of the metaphysical tenets that determine Christianity are disprovable. While many of his contemporaries look down at the sciences as irrelevant to philosophical or theological questions, his work shows that science is far more powerful and dangerous to ideological systems than anyone had imagined.
Galileo's agnosticism—his attempt to show empirically that God is perhaps not a physically knowable entity—is highly subversive in the society in which he lives. He lives in a society that is skeptical about the discoveries he makes, in which empirical proof does not go as far as he would like it to, and hardly anyone shares his enthusiasm for his theories. In fact, as Sagredo warns him, the masses are not particularly open to proof, attached as they are to the beliefs that they have always taken for granted.
Not only does Galileo believe in the power of his theories to change how people understand the universe, but he is also exceedingly confident that he will be able to convince the world of the importance of his discoveries. He insists that every man wants to understand the world, that knowledge is one of the greatest pleasures of existence, and that reason is always ennobling. Sagredo is not so sure, and seems confident that Galileo's theories will be met with resistance, cynically noting, "What kind of person is said to go into things with his eyes open?" While Galileo is sure that his desire to understand the truths of science is a universal impulse, Sagredo is sure that people would rather remain ignorant.
One of Galileo's defining characteristics is his dogged pursuit of truth. Even in the face of the outbreak of plague, which has led everyone to flee the city, Galileo is tied to his notes, and is determined not to abandon all his work. Death is knocking on his door, but Galileo is undeterred, so passionate is he about proving his theory of the universe. This plot point shows Galileo's commitment to truth and his intellectual pursuits, a commitment that withstands the danger of sickness.
