"Because the old days are over and this is a new time."
Galileo has a strong faith in mankind and its truth-seeking abilities. He is absolutely sure that “the old days are over and this is a new time." However, he proves to be horribly wrong, for people do not want to perceive that truth, and would rather stay ignorant to the ways of the world.
"Truth is born of the times, not of authority."
Having understood that his guests are going to deny the truth as long as they need to, Galileo tries to make them understand that “truth is born if the times, not of authority." He hope is that truth’s gravity might help him to break the wall of society's ignorance, but nothing seems to work. He asks them not to ask “where truth is leading,” and instead just to follow it.
"Do you imagine he will merely note in his diary: January 10th 1610—got rid of heaven?"
Although Galileo is a wise man, he is also rather naïve. Somehow he manages to convince himself that everyone is going to be amenable to him proving that the Copernican system is the correct one. One of his acquaintances, Sagredo, tries to show him just how dangerous his ideas might actually be, suggesting that Galileo's work has the potential to completely destroy Judeo-Christian ideology in a way that church officials will not easily take to.
"You made an unfortunate choice of subject, Mr. Galilei."
The procurator says this to Galileo to suggest that his choosing to study science, while intellectually stimulating, is not a particularly lucrative field. After Galileo complains to him about his low salary, the procurator blames it on the fact that it is not popular in the marketplace, rather than the fact that the economic system does not reward innovation.
"There are phenomena that present difficulties for us astronomers, but does mankind have to understand everything?"
An astronomer says this to Galileo at the Collegium Romanum, protesting Galileo's discoveries by suggesting that it is better for them to remain in ignorance than to question every little detail of science. This line represents the kind of willful ignorance against which Galileo is fighting.
"They have been assured that God's eye is always on them—probingly, even anxiously—: that the whole drama of the world is constructed around them so that they, the performers, may prove themselves in their greater or lesser roles."
The Little Monk says this to Galileo in the Florentine Ambassador's palace in Rome. He speaks about his parents, simple olive farmers, whose belief in God keeps them tied to their poverty, uncritical of the structures that oppress them. In their view, because God is all-knowing, they are living a life that has been determined for them and which is beyond criticism. The implications of Galileo's findings are enormous, in that they promise to break through this false sense of determinism, and give some autonomy to the average working person.
"Virtues are not an offshoot of poverty, my dear fellow."
This is Galileo's response to the Little Monk's claims. While the Little Monk suggests that poverty is somehow ennobling, at least in the eyes of his working-class parents, Galileo suggests that virtue is independent of struggle, and that those who have less ought to have a critical relationship to the world around them, and not imagine that they are the more virtuous just because they are poor.
"All you gentlemen need do is look through the telescope!"
When the Grand Duke and the courtly scholars visit Galileo's study, they insist that they only believe in the Aristotelian model of the universe, not the Copernican one that Galileo is trying to prove using his telescope. Ever optimistic that people will be persuaded by seeing the truth in front of them, Galileo urges them to look through his telescope to see for themselves, but they do not.
"Someone who doesn't know the truth is just thick-headed. But someone who does know it and calls it a lie is a crook."
Galileo says this to Mucius, to explain the fact that he thinks it is not just that the authorities are ignorant, but that they are willfully corrupt. In choosing not to believe the empirical evidence that Galileo has set forth with his studies, the scholars are committing a grave offense and are little more than "crooks" in his estimation.
"Unhappy the land that has no heroes!"
Andrea says this after his mentor, Galileo, recants. He is heartbroken about the fact that his chief role model, the man who taught him to believe in the truth, has caved to the pressure of the Inquisition and pretended not to believe the truths that he so adamantly supports.
