Galileo Galilei 1564–1642
Italian astronomer, mathematician, physicist, and philosopher.
Galileo is regarded as one of the greatest scientific thinkers of the Renaissance. His questioning of Aristotelian and Ptolemaic concepts of physics and astronomy, his studies of motion, his refinement of the telescope, and his subsequent discoveries about the universe were to have far-reaching, influential effects on the way people think about the earth and the heavens. Galileo's ideas also got him into trouble: condemned by the Inquisition for espousing a heliocentric world system, which violated Catholic Church teachings that the Earth was the center of the universe, he spent the last years of his life under house arrest.
Galileo Galilei was born in Pisa in 1564 to a cloth merchant/musician and member of the minor nobility. In 1581 he enrolled at the University of Pisa as a medical student, but his interests soon turned to the field of mathematics, and he received a teaching position at the University in 1589. From the beginning, Galileo's strong disagreement with popular Aristotelian theories of motion and gravity led him into conflict with his academic peers, and he was eventually forced to resign as Chair of Mathematics at Pisa. In 1592, however, he was appointed Professor of Mathematics at Padua. On vacation from the University of Padua in 1605 he tutored Cosimo, the Prince of Tuscany. Cosimo was later to become the Grand Duke of Tuscany and Galileo's patron. And it was to the Grand Duke's mother, Christina, that Galileo wrote his fateful Lettera a Madama Cristina de Lorena (written 1615; published 1636; Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany), in which he unsuccessfully attempted to reconcile the Church and Biblical exegesis with the Copemican heliocentric system. Well before this disastrous event, however, a supernova occurred in 1604; it was visible to the human eye and drew Galileo into a heated debate with those who believed in Aristotle's theory that the heavens were immutable. Galileo's life took a decisive turn in 1608 with the invention of the telescope in Holland. A year later, Galileo made refinements to the telescope which allowed him to view not only the stars in the Milky Way but also four moons around Jupiter, spots on the sun, and the rugged and uneven surface of the earth's
moon. Galileo published these findings in Sidereus nuncius (1610; The Starry Messenger) in which he began to think seriously about the likelihood of a Copernican universe. The Starry Messenger was well-received, but a later, more candid discussion of Copernicanism, published in 1613 as Historia e dimonstrazioni intorno alle macchie solari (Sunspot Letters) was condemned by the Church as an outspoken defense of heliocentrism. In 1625, Galileo began working on a discourse entitled Dialogo dei due massimi sistemi del mondo—Tolemaico e Copernicano (1632; Dialogue Concerning the Two Chief World Systems). This venture initially received Pope Urban VIII's blessing as a measured discussion of the compatibility of Church doctrine and the Copernican system. After it was written, however, the Pontiff criticized the Dialogue for two reasons: first, he felt that he himself had been portrayed as an object of ridicule in the discourse; and second, he was notified of the apparent existence of a document signed by Galileo in 1616 promising never again to advocate or even discuss Copernicanism. Events happened fairly quickly after that: In February of 1632, the Dialogue was published; in October of that same year, Galileo was ordered to come to Rome to answer before the Inquisition. In June of 1633, Galileo was compelled to repudiate the Dialogue on his knees before his accusers. He was sentenced as a heretic and condemned to imprisonment for life—a sentence that was softened to house arrest with the understanding that Galileo would never again publish his writings. When he died in 1642, he was blind but still publishing—although outside Italy. To the end of his life, Galileo insisted that there was no conflict between Copernicanism and his own devotion to the Church.
Galileo's major works include The Starry Messenger, which generated much positive excitement when it focused people's eyes for the first time on what was actually happening in the sky. His Sunspot Letters, on the other hand, are notorious. As Stillman Drake points out, Galileo wrote these Letters in Italian rather than in Latin (a scholarly and liturgical language that was universal only to those who were educated); by contrast, the colloquial Letters were accessible to "practically everyone in Italy who could read." Significantly, the arguments contained in them described a Copernican or heliocentric universe rather than the Ptolemaic or world-centered universe advocated by the Church. Galileo's most famous work, the Dialogue Concerning the Two Chief World Systems, is well-known not for its rigid defense of the Copernican against the Ptolemaic system (for it was meant to consider the two impartially); instead, it is infamous because Galileo wrote it after he had apparently been forbidden to write or teach anything at all about the Copernican system. Thus the Dialogue was catalyst for Galileo's appearance and conviction before the Inquisition. Ironically, as Jean Dietz Moss points out, it is the Letter to the Grand Duchess Christina where Galileo unequivocally advocates the Copernican system. Yet he does so while trying to prove that heliocentrism and the interpretation of the Bible are not at odds. Thus, it has "become a classic in literature relating to the conflict between science and religion," and "passages [from it] are often quoted for the sheer power of their expression and the acuity of their observations."
Today, experts on the life and works of Galileo are increasingly coming to believe that he was a victim not of his ideas, but of politics. Several scholars have called into question the very existence of the document of 1616 in which Galileo was supposed to have promised never to teach or write about the Copernican system. Instead, some specialists now argue that the sharptongued and not always diplomatic Galileo became a convenient pawn in a power struggle between members of the Church of Rome as a result of the Counter-Reformation—a time when the Catholic Church was trying to reform itself in response to the Protestant Reformation. As Maurice A. Finocchiaro observes, Galileo's trial occurred "during the so-called Thirty Years War between Catholics and Protestants…." At that time "Pope Urban VIII, who had earlier been an admirer and supporter of Galileo, was in an especially vulnerable position; thus not only could he not continue to protect Galileo, but he had to use Galileo as a scapegoat to reassert … his authority and power."
De motu [On Motion] (originally untitled treatise) 1589?
Sidereus nuncius [The Starry Messenger; also translated as The Sidereal Messenger; or as Astronomical Announcement] (essay) 1610
Discorso intorno alle cose che stanno su l'acqua [Discourse on Floating Bodies; also translated as Discourse on Bodies in Water] (essay) 1612
Historia e dimonstrazioni intorno alle macchie solari [Sunspot Letters; also translated as Letters on Sunspots] (letters) 1613
Lettera a Madama Cristina de Lorena [Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany; also translated as Letter to the Grand Duchess Christina; or simply, Letter to Christina] (treatise) written 1615; published 1636
Il saggiatore [The Assayer] (essay) 1623
Dialogo dei due massimi sistemi del mondo—Tolemaico e Copernicano [Dialogue on the Two Principal World Systems—Ptolemaic and Copernican; also translated as Dialogue Concerning the Two Chief World Systems; also referred to as Dialogue] (dialogue) 1632
Discorsi e dimostrazioni matematiche intorno a due nuove scienze … [Mathematical Discourses and Demonstrations, Touching Two New Sciences … ] (essay) 1638
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SOURCE: "Galileo," in Great Astronomers, Isbister and Company, Ltd., 1895, pp. 67-95.
[In the following excerpt, Ball gives a nineteenth-century perspective of Galileo's life and career, focusing in particular on letters from his daughter Sister Maria Celeste.]
Among the ranks of the great astronomers it would be difficult to find one whose life presents more interesting features and remarkable vicissitudes than does that of Galileo. We may consider him as the patient investigator and brilliant discoverer. We may consider him in his private relations, especially to his daughter, Sister Maria Celeste, a woman of very remarkable character; and we have also the pathetic drama at the close of Galileo's life, when the philosopher drew down upon himself the thunders of the Inquisition.
The materials for the sketch of this astonishing man are sufficiently abundant. We make special use in this place of those charming letters which his daughter wrote to him from her convent home. More than a hundred of these have been preserved, and it may well be doubted whether any more beautiful and touching series of letters addressed to a parent by a dearly loved child have ever been written. An admirable account of this correspondence is contained in a little book entitled The Private Life of Galileo, published anonymously by Messrs. Macmillan in 1870, and I have been much indebted to the author of...
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SOURCE: Foreword to Galileo Galilei: "Dialogue Concerning the Two Chief World Systems—Ptolemaic & Copernican," by Galileo Galilei, translated by Stillman Drake, with the foreward translated by Sonja Bargmann, University of California Press, 2nd ed., 1967, pp. vii-xix.
[In the following essay, originally published in 1953 and reprinted in 1967, Einstein expresses his admiration for Galileo's creativity and remarks that the theme of "Galileo's work is the passionate fight against any kind of dogma based on authority."]
Galileo's Dialogue Concerning the Two Chief World Systems is a mine of information for anyone interested in the cultural history of the Western world and its influence upon economic and political development.
A man is here revealed who possesses the passionate will, the intelligence, and the courage to stand up as the representative of rational thinking against the host of those who, relying on the ignorance of the people and the indolence of teachers in priest's and scholar's garb, maintain and defend their positions of authority. His unusual literary gift enables him to address the educated men of his age in such clear and impressive language as to overcome the anthropocentric and mythical thinking of his contemporaries and to lead them back to an objective and causal attitude toward the cosmos, an attitude which had become lost to humanity with the decline...
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SOURCE: "Galileo in the Present," in Homage to Galileo: Papers Presented at the Galileo Quadricentennial, University of Rochester, October 8 and 9, 1964, edited by Morton F. Kaplon, The M.I.T. Press, 1965, pp. 1-25.
[In the following essay, first presented as a paper in 1964 and published in 1965, de Santillana argues that Galileo was the first to combine the study of science with the usefulness of technology, or "technique," in order to find out the "how" of things in nature.]
Galileo has by now moved out of history into myth. He is more than the creator of an era. He has become a hero of civilization, the symbol of a great adventure like Prometheus, or rather like the Ulysses of Dante and Tennyson.
There was in his earlier triumph the note of divine surprise, of an incredible world opening up. There also is, later, darkness closing in on the hero. Let me quote a famous letter of his to Diodati from 1638:
Alas, honoured Sir, Galileo, your dear friend and servant, has become by now irremediably blind. Your Honour may understand in what affliction I find myself, as I consider how that heaven, that world, that universe, that by my observations and clear demonstrations I had amplified a hundred and a thousand times over what had been seen and known by the learned of all past centuries, has now shrunk for me to the space occupied by my person....
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SOURCE: "The Effectiveness of Galileo's Work," in Galileo Studies: Personality, Tradition, and Revolution, The University of Michigan Press, 1970, pp. 95-122.
[In the following excerpt, Drake asserts that Galileo was revolutionary for being the first to integrate the heretofore separate disciplines of mathematics, physics, and astronomy in scientific thought.]
Until the present century it was customary to call Galileo the founder of modern physical science. Ancient science was thought of as having ended with the decline of Greek civilization, and no real contribution to scientific thought was known to have been made during the long ensuing period to the late Renaissance. The seemingly abrupt emergence of many recognizably modern scientific concepts early in the seventeenth century thus appeared to have been a true revolution in human thought. In that scientific revolution, Galileo appeared as the prime mover. The persecution that he suffered as a result of his active propagation of new ideas lent color to the idea that his had been a totally new and revolutionary kind of science.
As historians of ideas gave more careful attention to the treatment of scientific questions in medieval and early Renaissance times, the traditional role that had rather romantically been assigned to Galileo was critically reexamined. Many early anticipations of modern science or its fundamental concepts were...
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SOURCE: "Epilogue: 'The Greatness of Galileo Is Known to All,'" in Galileo Galilei: Toward a Resolution of 350 Years of Debate—1633-1983, edited by Paul Cardinal Poupard, with the "Epilogue" translated by Ian Campbell from a speech given in 1979, Duquesne University Press, 1987, pp. 195-200.
[In the following essay, first presented as a speech in 1979 and reprinted in 1987, Pope John Paul II undertakes to reconcile the views of the Catholic Church with those of Galileo, arguing that Galileo was not in fact in opposition to the Church.]
During the centenary commemoration of the birth of Albert Einstein,1 celebrated by the Pontifical Academy of the Sciences on November 10, 1979, Pope John Paul II spoke on the profound harmony between the truth of faith and the truth of science in the following terms.
I feel myself to be fully one with my predecessor Pius XI, and with the two who followed him in the Chair of Peter, in inviting the members of the Academy of the Sciences and all scientists with them, to bring about "the ever more noble and intense progress of the sciences, without asking any more from them; and this is because in this excellent proposal and this noble work there consists that mission of serving truth with which we charge them."2
The search for truth is the fundamental task of science. The researcher who moves on this plane of...
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SOURCE: "Galileo's Letter to Christina: Some Rhetorical Considerations," in Renaissance Quarterly, Vol. XXXVI, No. 4, Winter, 1983, pp. 547-76.
[In the following essay, Moss argues that Galileo's letter to his patron's mother, the Grand Duchess of Tuscany, in which he defends his position on Copernicus would have been more likely to save him had it stayed within his own area of expertise—mathematics—rather than strayed into theology, the specialty of his accusers.]
The year 1982 marked the 350th anniversary of the publication of Galileo's Dialogue Concerning the Two Chief World Systems, a work that was to have a tragic impact on the astronomer's life, and also on the relations between science and religion. It was the publication of the Dialogue that precipitated the trial of Galileo before the Inquisition on charges of teaching the Copernican system, which had been condemned in 1616. The book sets forth the inadequacies of the Ptolemaic system and the superiority of the Copernican for "saving the appearances" of celestial motion, but it does not press openly for acceptance of the theory. An earlier writing of Galileo, the Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany, referred to in short as the Letter to Christina, does just that. It was written in 1615 before the opinion on Copernicanism was delivered, and written, moreover, to dissuade the...
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SOURCE: "Science and Patronage: Galileo and the Telescope," in Isis, Vol. 76, March, 1985, pp. 11-30.
[In the following essay, Westfall argues that the heavy reliance upon and competition for patronage in the seventeenth century might have affected the truthfulness of some of the scientific conclusions and discoveries made by scientists of that period, including Galileo.]
Sometime late in 1610, probably near 11 December, Galileo received a letter from his disciple Benedetto Castelli:
If the position of Copernicus, that Venus revolves around the sun, is true (as I believe), [Castelli wrote], it is clear that it would necessarily sometimes be seen by us horned and sometimes not, even though the planet maintains the same position relative to the sun…. Now I want to know from you if you, with the help of your marvellous glasses, have observed such a phenomenon, which will be, beyond doubt, a sure means to convince even the most obstinate mind. I also suspect a similar thing with Mars near the quadrature with the sun; I don't mean a horned or non-horned shape, but only a semicircular and a more full one.1
How readily the passage summons up familiar images of Galileo, the Copernican polemicist, who turned the telescope on the heavens, if not first, surely first in an effective manner, and with his discoveries forever transformed...
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SOURCE: "Galileo: Physics and Astronomy," in The Galileo Connection: Resolving Conflicts between Science and the Bible, Intervarsity Press, 1986, pp. 81-102.
[In the following excerpt, Hummel outlines Galileo's early years, and describes the steps in Galileo's own particular scientific method.]
Renaissance Italy was a collection of states with a wide variety of governmental structures. In one the people might hold power; another would have a hereditary ruler. Such diversity fostered the idea that there could be more than one way to govern. Differences of opinion on economic and social issues flourished. In that relatively open society, ready in many areas to consider new ideas, Galileo Galilei began his education.
In two arenas, however, the strong hand of authority maintained a firm grip. The Roman Catholic Church had a monopoly on religious life, and Aristotelian philosophy dominated science in the universities. Yet in Galileo's time both institutions found themselves on the defensive against swirling currents of Reformation and Renaissance. Those currents converged in the life and work of this controversial figure sometimes called the father of modern science. Few episodes in the history of science have generated more intense debate than the ecclesiastical condemnation of Copernicus's astronomy in 1616 and the trial of Galileo in 1633. In one form or another that controversy...
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SOURCE: "Galileo and the Church," in God and Nature: Historical Essays on the Encounter between Christianity and Science, edited by David C. Lindberg and Ronald L. Numbers, University of California Press, 1986, pp. 114-35.
[In the following essay, Shea details the theological, political, and scientific temper of the era and country in which Galileo lived, and argues that Galileo was more a victim of politics than of inflexible beliefs.]
The condemnation of Galileo (1564-1642) is perhaps the most dramatic incident in the long and varied history of the relations between science and religious faith. Honest seekers after truth have been shocked by the attempt to suppress the claim that the earth moves and have seen in the trial of Galileo decisive evidence that religion is dangerous, not only when willfully perverted to secular ends but also, and perhaps more especially, when pursued by sincere men who consider themselves the stewards of God's revealed truth.' But Galileo's condemnation must be seen in historical perspective. We must remember that he was born in 1564, the year after the close of the Council of Trent, which may be considered as setting the tone of Roman Catholicism until a new spirit came to prevail with John XXIII in our own century. The opposition he encountered can only be understood if it is related to a period in which modern liberal values were far from commanding the assent that we...
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SOURCE: "Bellarmino, Galileo, and the Clash of Two World Views," in Essays on the Trial of Galileo, Vatican Observatory Publications, 1989, pp. 1-30.
[In the following essay, Westfall summarizes the backgrounds of Galileo and his adversary, Cardinal Bellarmino (also known as Bellarmine), and argues that their conflict regarding Galileo's officially heretical belief in a Copernican or heliocentric universe began as early as 1610 with the publication of Sidereus nuncius (The Starry Messenger).]
And because it has also come to the attention of the aforementioned Sacred Congregation [the final paragraph of a decree of 5 March 1616 by the Congregation of the Index stated] that the Pythagorean doctrine concerning the mobility of the earth and the immobility of the sun, which Nicholas Copernicus, De revolutionibus orbium coelestium, and Diego de Zùñiga [in his commentary] on Job also taught, and which is false and altogether incompatible with divine Scripture, is now spread abroad and accepted by many, as appears from a certain printed Epistle of a certain Carmelite Father [Foscarini] … ; therefore, in order that an opinion ruinous to Catholic truth not creep [serpat] further in this manner, the Sacred Congregation decrees that the said Nicholas Copernicus, De revolutionibus orbium, and Diego de Zùñiga on Job be suspended until corrected; that the book of the...
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SOURCE: Introduction to The Galileo Affair: A Documentary History, edited and translated by Maurice A. Finocchiaro, University of California Press, 1989, pp. 1-46.
[In the following excerpt, Finocchiaro describes Galileo 's personality as it clashed with the tenor of the times, and explains Copernicus 's heliocentric theory as well as its limitations, showing how, thanks to his improvements on the recently invented telescope, Galileo was able to eliminate most of those limitations.]
Beginning with personal or psychological factors, it is easy to see that Galileo had a penchant for controversy, was a master of wit and sarcasm, and wrote with unsurpassable eloquence. Interacting with each other and with his scientific and philosophical virtues, these qualities resulted in his making many enemies and getting involved in many other bitter disputes besides the main one that concerns us here. Typically these disputes involved questions of priority of invention or discovery and fundamental disagreements about the occurrence and interpretation of various natural phenomena. It may be of some interest to give a brief list of the other major controversies: a successful lawsuit against another inventor for plagiarism in regard to Galileo's invention of a calculating device and in regard to its accompanying instructions; a dispute with his philosophy colleagues at the...
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SOURCE: "Daniel 5 and the Assayer: Galileo Reads the Handwriting on the Wall," in The Journal of Medieval and Renaissance Studies, Vol. 21, No. 1, Spring, 1991, pp. 1-27.
[In the following essay, Reeves portrays Galileo's Assayer as a witty and rigorous linguistic attack against scientific ignorance and vanity.]
In that great catalog of wit and invective which Galileo Galilei published in 1623 as the Assayer, the rather unlikely issue of Babylonian cookery is singled out as particularly deserving of ridicule. The matter arose in the course of the debate over the comets of 1618—the ostensible subject of the Assayer—between Galileo and his opponent Orazio Grassi, S.J., when the latter maintained that motion, not friction, was the cause of heat. Grassi offered as proof several verses from Ovid, Lucan, Lucretius, and Virgil in which arrows were ignited or even melted as they flew through the air; not content with mere poetry, he enhanced his argument with the testimony of the tenth-century lexicographer Suidas, a man "of great authority and trustworthiness,"1 who had written that "the Babylonians, whirling eggs in slings, were no strangers to the simple diet of the hunter, but rather accustomed to the demands of the wilderness, such that they were able to cook even raw eggs by this motion."2
It is reasonable to...
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SOURCE: "The Storm Breaks Loose: The Trial and Condemnation of Galileo," in Galileo: For Copernicanism and for the Church, translated by George V. Coyne, S. J., Vatican Observatory Publications, 1994, pp. 369-462.
[In the following excerpt, Fantoli provides transcripts of Galileo's questioning by the Inquisition and his testimony concerning the publication of his Dialogue.]
6. The Trial of 1633 and Galileo's Defense
Finally the two-month long uncertainty came to an end. [Francesco Niccolini, Ambassador of the grand Duke of Tuscany to Rome's Holy See and spokesperson on behalf of Galileo,] was summoned by Cardinal Francesco Barberini, who informed him that by order of the Pope and of the Congregation of the Holy Office Galileo should be summoned to that same Holy Office. He also let him know that, as a special gesture of respect to the Grand Duke, since a few hours of interrogation would not be enough, it would perhaps be necessary to retain him at the Holy Office. Once more Niccolini tried to make clear the state of health of Galileo, who, as he wrote three days later to Cioli, "for two nights running here had groaned and complained continuously of his arthritic pains, of his age and of the suffering he would experience from all of this" (XV, 85) and he asked the cardinal if it would not be possible to allow him to return each evening to the embassy. But the cardinal did...
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Broderick, James. Galileo: The Man, His Work, His Misfortunes. New York: Harper and Row, 1964, 152 p.
Traces the life of Galileo as a man of "genius" forced to struggle against the outmoded ideas of Aristotle and of Ptolemy, as well as with the implacability of the Inquisition.
Drake, Stillman. Galileo at Work: His Scientific Biography. Chicago: The University of Chicago Press, 1978, 536 p.
Looks at Galileo's life from the point of view of his publications, with a particular focus on his lesser known writings.
——. Galileo. New York: Hill and Wang, 1980, 100 p.
Brief but comprehensive biography of the life, work, and trial of Galileo.
Fermi, Laura, and Bernardini, Gilberto. Galileo and the Scientific Revolution. New York: Basic Books, Inc., 1961, 150 p.
Looks at the personal as well as the scientific side of Galileo's life.
Geymonat, Ludovico. Galileo Galilei: A Biography and Inquiry into His Philosophy of Science. Translated by Stillman Drake. New York: McGraw-Hill, 1965, 260 p.
Examines Galileo's life from his childhood to his death, and includes a debate...
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