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Galileo Galilei
(15 Feb 1564 - 8 Jan 1642)

Italian natural philosopher who believed the Earth revolved around the Sun. For this, he was interrogated by the Inquisition, was put on trial, found guilty and sentenced to indefinite imprisonment. For renouncing his former beliefs before the Cardinals that judged him, he was allowed to serve this time instead under house-arrest.


Science Quotes by Galileo Galilei (34 quotes)

Galileo head and shoulders on starfield, w/earth in orbit around him with quotes “Eppur si muove” (Italian)+“And yet it moves”
By legend (likely not in fact), Galileo quietly whispered this to himself, after his confession.

Galileo Galilei portrait by Domenico Cresti da Passignano (or Passignani) - upper body
Galileo Galilei
by Domenico Cresti da Passignano (or Passignani) before 1642. (source)
Eppur si muove.
And yet it does move.
Referring to the Earth. Apocryphal saying (of doubtful authenticity). By legend, Galileo whispered this to himself as he rose from kneeling after making his abjuration of heliocentricity.
— Galileo Galilei
No clear evidence exists that Galileo actually said these words, which may have been invented as stories about Galileo were circulated after his death. Seen in print as early as L’Abbé Irailh, Querelles Littéraires [“Literary quarrels”] (Paris, 1761), Vol. 3, 49. As cited, with great skepticism, in John Joseph Fahie, Galileo, His Life and Work (1903), 325.
Science quotes on:  |  Abjuration (2)  |  Earth (250)  |  Heliocentric Model (7)

About ten months ago [1609] a report reached my ears that a certain Fleming [Hans Lippershey] had constructed a spyglass, by means of which visible objects, though very distant from the eye of the observer, were distinctly seen as if nearby... Of this truly remarkable effect several experiences were related, to which some persons gave credence while others denied them. A few days later the report was confirmed to me in a letter from a noble Frenchman at Paris, Jacques Badovere, which caused me to apply myself wholeheartedly to enquire into the means by which I might arrive at the invention of a similar instrument. This I did shortly afterwards, my basis being the theory of refraction. First I prepared a tube of lead, at the ends of which I fitted two glass lenses, both plane on one side while on the other side one was spherically convex and the other concave.
— Galileo Galilei
The Starry Messenger (1610), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 28-9.
Science quotes on:  |  Lens (8)  |  Telescope (44)

As to what Simplicius said last, that to contend whether the parts of the Sun, Moon, or other celestial body, separated from their whole, should naturally return to it, is a vanity, for that the case is impossible, it being clear by the demonstrations of Aristotle that the celestial bodies are impassible, impenetrable, unpartable, etc., I answer that none of the conditions whereby Aristotle distinguishes the celestial bodies from the elementary has any foundation other than what he deduces from the diversity of their natural motions; so that, if it is denied that the circular motion is peculiar to celestial bodies, and affirmed instead that it is agreeable to all naturally moveable bodies, one is led by necessary confidence to say either that the attributes of generated or ungenerated, alterable or unalterable, partable or unpartable, etc., equally and commonly apply to all bodies, as well to the celestial as to the elementary, or that Aristotle has badly and erroneously deduced those from the circular motion which he has assigned to celestial bodies.
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 45.
Science quotes on:  |  Aristotle (101)  |  Moon (78)  |  Orbit (36)  |  Star (132)  |  Sun (115)

But I do not feel obliged to believe that that same God who has endowed us with senses, reason, and intellect has intended to forgo their use and by some other means to give us knowledge which we can attain by them.
— Galileo Galilei
Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany: (1615). In Discoveries and Opinions of Galileo, trans. Stillman Drake (1957), 183.
Science quotes on:  |  God (234)  |  Knowledge (679)

But what exceeds all wonders, I have discovered four new planets and observed their proper and particular motions, different among themselves and from the motions of all the other stars; and these new planets move about another very large star [Jupiter] like Venus and Mercury, and perchance the other known planets, move about the Sun. As soon as this tract, which I shall send to all the philosophers and mathematicians as an announcement, is finished, I shall send a copy to the Most Serene Grand Duke, together with an excellent spyglass, so that he can verify all these truths.
— Galileo Galilei
Letter to the Tuscan Court, 30 Jan 1610. Quoted in Albert van Heiden (ed.), Siderius Nuncius or The Sidereal Messenger (1989), 18.
Science quotes on:  |  Jupiter (12)  |  Mercury (26)  |  Orbit (36)  |  Planet (84)  |  Sun (115)  |  Venus (8)

But, because my private lectures and domestic pupils are a great hinderance and intteruption of my studies, I wish to live entirely exempt from the former, and in great measure from the latter. … in short, I should wish to gain my bread from my writings.
Reply upon being offered a professorship.
— Galileo Galilei
Quoted in John Elliot Drinkwater Bethune, Life of Galileo Galilei (1832), 63.
Science quotes on:  |  Money (87)  |  Research (360)

Count what is countable, measure what is measurable, and what is not measurable, make measurable.
— Galileo Galilei
As quoted, without citation, in Institute of Public Administration, Administration (1967), 15 175.
Science quotes on:  |  Count (15)  |  Measure (12)

For the holy Bible and the phenomena of nature proceed alike from the divine Word, the former as the dictate of the Holy Ghost and the latter as the observant executrix of God's commands. It is necessary for the Bible, in order to be accommodated to the understanding of every man, to speak many things which appear to differ from the absolute truth so far as the bare meaning of the words is concerned. But Nature, on the other hand, is inexorable and immutable; she never transgresses the laws imposed upon her, or cares a whit whether her abstruse reasons and methods of operation are understandable to men. For that reason it appears that nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words.
— Galileo Galilei
Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany: Concerning the Use of Biblical Quotations in Matters of Science (1615), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 182-3.
Science quotes on:  |  Experiment (369)  |  God (234)  |  Law (273)  |  Nature (534)  |  Observation (264)  |  Truth (450)

I accepted the Copernican position several years ago and discovered from thence the causes of many natural effects which are doubtless inexplicable by the current theories. I have written up many reasons and refutations on the subject, but I have not dared until now to bring them into the open, being warned by the fortunes of Copernicus himself, our master, who procured for himself immortal fame among a few but stepped down among the great crowd (for this is how foolish people are to be numbered), only to be derided and dishonoured. I would dare publish my thoughts if there were many like you; but since there are not, I shall forbear.
— Galileo Galilei
Letter to Johannes Kepler, 4 Aug 1597. Quoted in G. de Santillana, Crime of Galileo (1955), 11.
Science quotes on:  |  Nicolaus Copernicus (30)  |  Heliocentric Model (7)  |  Publication (75)

I cannot but be astonished that Sarsi should persist in trying to prove by means of witnesses something that I may see for myself at any time by means of experiment. Witnesses are examined in doutbful matters which are past and transient, not in those which are actual and present. A judge must seek by means of witnesses to determine whether Peter injured John last night, but not whether John was injured, since the judge can see that for himself.
— Galileo Galilei
'The Assayer' (1623), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 271.
Science quotes on:  |  Experiment (369)  |  Observation (264)  |  Truth (450)

I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations.
Referring to his pioneering telescope observations.
— Galileo Galilei
The Starry Messenger (Mar 1610). Quoted in Edmund Blair Bolles, Galileo's Commandment (1999), 104.
Science quotes on:  |  Jupiter (12)  |  Mercury (26)  |  Observation (264)  |  Telescope (44)  |  Venus (8)

I would beg the wise and learned fathers (of the church) to consider with all diligence the difference which exists between matters of mere opinion and matters of demonstration. ... [I]t is not in the power of professors of the demonstrative sciences to alter their opinions at will, so as to be now of one way of thinking and now of another. ... [D]emonstrated conclusions about things in nature of the heavens, do not admit of being altered with the same ease as opinions to what is permissible or not, under a contract, mortgage, or bill of exchange.
— Galileo Galilei
Letter to Cristina di Lorena, Grand Duchess of Tuscany (the mother of his patron Cosmo), 1615. Quoted in Sedley Taylor, 'Galileo and Papal Infallibility' (Dec 1873), in Macmillan's Magazine: November 1873 to April 1874 (1874) Vol 29, 94.
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I would say here something that was heard from an ecclesiastic of the most eminent degree [Cardinal Baronius (1538-1607)]: “That the intention of the holy ghost is to teach us how one goes to heaven, not how heaven goes.”
— Galileo Galilei
Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany: concerning the Use of Biblical Quotations in Matters of Science (1611 5), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 186.
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I would say here something that was heard from an ecclesiastic of the most eminent degree: 'That the intention of the Holy Ghost is to teach us how one goes to heaven, not how heaven goes.
— Galileo Galilei
Letter to Cristina di Lorena, Grand Duchess of Tuscany (the mother of his patron Cosmo), 1615. Translation as given in the Galilean Library web page www.galilean-library.org/manuscript.php?postid=43841.
Science quotes on:  |  Heaven (55)  |  Intention (20)  |  Teach (19)

I, Galileo Galilei, son of the late Vincenzo Galilei, of Florence, aged seventy years, being brought personally to judgment, and kneeling before your Most Eminent and Most Reverend Lords Cardinals, General Inquisitors of the universal Christian republic against heretical depravity, having before my eyes the Holy Gospels, which I touch with my own hands, swear that I have always believed, and now believe, and with the help of God will in future believe, every article which the Holy Catholic and Apostolic Church of Rome holds, teaches, and preaches. But because I have been enjoined by this Holy Office altogether to abandon the false opinion which maintains that the sun is the centre and immovable, and forbidden to hold, defend, or teach the said false doctrine in any manner, and after it hath been signified to me that the said doctrine is repugnant with the Holy Scripture, I have written and printed a book, in which I treat of the same doctrine now condemned, and adduce reasons with great force in support of the same, without giving any solution, and therefore have been judged grievously suspected of heresy; that is to say, that I held and believed that the sun is the centre of the universe and is immovable, and that the earth is not the centre and is movable; willing, therefore, to remove from the minds of your Eminences, and of every Catholic Christian, this vehement suspicion rightfully entertained toward me, with a sincere heart and unfeigned faith, I abjure, curse, and detest the said errors and heresies, and generally every other error and sect contrary to Holy Church; and I swear that I will never more in future say or assert anything verbally, or in writing, which may give rise to a similar suspicion of me; but if I shall know any heretic, or anyone suspected of heresy, that I will denounce him to this Holy Office, or to the Inquisitor or Ordinary of the place where I may be; I swear, moreover, and promise, that I will fulfil and observe fully, all the penances which have been or shall be laid on me by this Holy Office. But if it shall happen that I violate any of my said promises, oaths, and protestations (which God avert!), I subject myself to all the pains and punishments which have been decreed and promulgated by the sacred canons, and other general and particular constitutions, against delinquents of this description. So may God help me, and his Holy Gospels which I touch with my own hands. I, the above-named Galileo Galilei, have abjured, sworn, promised, and bound myself as above, and in witness thereof with my own hand have subscribed this present writing of my abjuration, which I have recited word for word. At Rome, in the Convent of Minerva, June 22, 1633. I, Galileo Galilei, have abjured as above with my own hand.
— Galileo Galilei
Abjuration, 22 Jun 1633
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If experiments are performed thousands of times at all seasons and in every place without once producing the effects mentioned by your philosophers, poets, and historians, this will mean nothing and we must believe their words rather our own eyes? But what if I find for you a state of the air that has all the conditions you say are required, and still the egg is not cooked nor the lead ball destroyed? Alas! I should be wasting my efforts... for all too prudently you have secured your position by saying that 'there is needed for this effect violent motion, a great quantity of exhalations, a highly attenuated material and whatever else conduces to it.' This 'whatever else' is what beats me, and gives you a blessed harbor, a sanctuary completely secure.
— Galileo Galilei
'The Assayer' (1623), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 273.
Science quotes on:  |  Experiment (369)  |  Philosophy (132)

In my studies of astronomy and philosophy I hold this opinion about the universe, that the Sun remains fixed in the centre of the circle of heavenly bodies, without changing its place; and the Earth, turning upon itself, moves round the Sun.
— Galileo Galilei
Letter to Cristina di Lorena, Grand Duchess of Tuscany (the mother of his patron Cosmo), 1615. Quoted in Sedley Taylor, 'Galileo and Papal Infallibility' (Dec 1873), in Macmillan's Magazine: November 1873 to April 1874 (1874) Vol 29, 93.
Science quotes on:  |  Astronomy (105)  |  Earth (250)  |  Heliocentric Model (7)  |  Opinion (81)  |  Sun (115)

In questions of science the authority of a thousand is not worth the humble reasoning of a single individual.
— Galileo Galilei
Attributed by F. Arago.
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It reveals to me the causes of many natural phenomena that are entirely incomprehensible in the light of the generally accepted hypotheses. To refute the latter I collected many proofs, but I do not publish them ... I would dare to publish my speculations if there were people men like you.
[Declaring his belief in the heliocentric theory of Copernicus.]
— Galileo Galilei
Letter to Kepler (1596). Quoted in Will Durant, Ariel Duran, The Age of Reason Begins (1961), 603. From Hermann Kesten, Copernicus and His World, translated by E.B. Ashton (pseud.) and Norbert Guterman (1945), 348-349.
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Many of the nobles and senators, although of great age, mounted more than once to the top of the highest church in Venice, in order to see sails and shipping … so far off that it was two hours before they were seen without my spy-glass …, for the effect of my instrument is such that it makes an object fifty miles off appear as large as if it were only five miles away. ... The Senate, knowing the way in which I had served it for seventeen years at Padua, ... ordered my election to the professorship for life.
— Galileo Galilei
Quoted in Will Durant, Ariel Duran, The Age of Reason Begins (1961), 604. From Charles Singer, Studies in the History and Method of Science (1917), Vol. 1, 228.
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Mathematics is the key and door to the sciences.
— Galileo Galilei
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Nor need you doubt that Pythagoras, a long time before he found the demonstration for the Hecatomb, had been certain that the square of the side subtending the right angle in a rectangular triangle was equal to the square of the other two sides; the certainty of the conclusion helped not a little in the search for a demonstration. But whatever was the method of Aristotle, and whether his arguing a priori preceded sense a posteriori, or the contrary, it is sufficient that the same Aristotle (as has often been said) put sensible experiences before all discourses. As to the arguments a priori, their force has already been examined.
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 60.
Science quotes on:  |  Aristotle (101)  |  Observation (264)  |  Pythagoras (17)

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.
— Galileo Galilei
'The Assayer' (1623), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 237-8.
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Science proceeds more by what it has learned to ignore than what it takes into account.
— Galileo Galilei
Found in David Hatcher Childress and Bill Clendenon, Atlantis & the Power System of the Gods (2002), 191. [Quote may be questionable since no major source found by Webmaster. If you have information on a primary source, please contact Webmaster.]
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Take note, theologians, that in your desire to make matters of faith out of propositions relating to the fixity of sun and earth you run the risk of eventually having to condemn as heretics those who would declare the earth to stand still and the sun to change position—eventually, I say, at such a time as it might be physically or logically proved that the earth moves and the sun stands still.
— Galileo Galilei
Note added by Galileo in the preliminary leaves of his copy of Dialogue on the Great World Systems (1632).
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That sculpture is more admirable than painting for the reason that it contains relief and painting does not is completely false. ... Rather, how much more admirable the painting must be considered, if having no relief at all, it appears to have as much as sculpture!
— Galileo Galilei
Letter to Ludovico Cigoli. Quoted in Robert Enggass, Jonathan Brown, Italian and Spanish Art, 1600-1750 (1992), 22.
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The Grand Duke [of Tuscany] …after observing the Medicaean plants several times with me … has now invited me to attach myself to him with the annual salary of one thousand florins, and with the title of Philosopher and Principal Mathematicial to His Highness; without the duties of office to perform, but with the most complete leisure; so that I can complete my Treatises...
— Galileo Galilei
From a letter to Kepler. Quoted in John Elliot Drinkwater Bethune, Life of Galileo Galilei (1832), 63.
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The prohibition of science would be contrary to the Bible, which in hundreds of places teaches us how the greatness and the glory of God shine forth marvelously in all His works, and is to be read above all in the open book of the heavens. And let no one believe that the reading of the most exalted thoughts which are inscribed upon these pages is to be accomplished through merely staring up at the radiance of the stars. There are such profound secrets and such lofty conceptions that the night labors and the researches of hundreds and yet hundreds of the keenest minds, in investigations extending over thousands of years would not penetrate them, and the delight of the searching and finding endures forever.
— Galileo Galilei
As stated by William H. Hobbs, 'The Making of Scientific Theories,' Address of the president of Michigan Academy of Science at the Annual Meeting, Ann Arbor (28 Mar 1917) in Science (11 May 1917), N.S. 45, No. 1167, 443.
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Their vain presumption of knowing all can take beginning solely from their never having known anything; for if one has but once experienced the perfect knowledge of one thing, and truly tasted what it is to know, he shall perceive that of infinite other conclusions he understands not so much as one.
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 112.
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Two truths cannot contradict one another.
— Galileo Galilei
Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany: concerning the Use of Biblical Quotations in Matters of Science (1615), Maurice A. Finocchiaro (trans.) The Essential Galileo (2008), 120. Also expressed in Letter to Castelli (1613) as “it is impossible for two truths to contradict wach other” (p.107). However, the concept predates Galileo, and was, for example, expressed by Averroes.
Science quotes on:  |  Truth (450)

We see only the simple motion of descent, since that other circular one common to the Earth, the tower, and ourselves remains imperceptible. There remains perceptible to us only that of the stone, which is not shared by us; and, because of this, sense shows it as by a straight line, always parallel to the tower, which is built upright and perpendicular upon the terrestrial surface.
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 177.
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When the moon is ninety degrees away from the sun it sees but half the earth illuminated (the western half). For the other (the eastern half) is enveloped in night. Hence the moon itself is illuminated less brightly from the earth, and as a result its secondary light appears fainter to us.
— Galileo Galilei
The Starry Messenger (1610), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 45.
Science quotes on:  |  Moon (78)

[Simplicio] is much puzzled and perplexed. I think I hear him say, 'To whom then should we repair for the decision of our controversies if Aristotle were removed from the choir? What other author should we follow in the schools, academies, and studies? What philosopher has written all the divisions of Natural Philosophy, and so methodically, without omitting as much as a single conclusion? Shall we then overthrow the building under which so many voyagers find shelter? Shall we destroy that sanctuary, that Prytaneum, where so many students find commodious harbour; where without exposing himself to the injuries of the air, with only the turning over of a few leaves, one may learn all the secrets of Nature.'
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 66.
Science quotes on:  |  Aristotle (101)

…I distinguish two parts of it, which I call respectively the brighter and the darker. The brighter seems to suround and pervade the whole hemisphere; but the darker part, like a sort of cloud, discolours the Moon's surface and makes it appear covered with spots. Now these spots, as they are somewhat dark and of considerable size, are plain to everyone and every age has seen them, wherefore I will call them great or ancient spots, to distinguish them from other spots, smaller in size, but so thickly scattered that they sprinkle the whole surface of the Moon, but especially the brighter portion of it. These spots have never been observed by anyone before me; and from my observations of them, often repeated, I have been led to the opinion which I have expressed, namely, that I feel sure that the surface of the Moon is not perfectly smooth, free from inequalities and exactly spherical... but that, on the contrary, it is full of inequalities, uneven, full of hollows and protuberances, just like the surface of the Earth itself, which is varied everywhere by lofty mountains and deep valleys.
Describing his pioneering telecope observations of the Moon made from Jan 1610.
— Galileo Galilei
The Starry Messenger (Mar 1610). Quoted in Patrick Moore, Patrick Moore on the Moon (2006), 56.
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Quotes by others about Galileo Galilei (30)

Science would not be what it is if there had not been a Galileo, a Newton or a Lavoisier, any more than music would be what it is if Bach, Beethoven and Wagner had never lived. The world as we know it is the product of its geniuses—and there may be evil as well as beneficent genius—and to deny that fact, is to stultify all history, whether it be that of the intellectual or the economic world.
What is Science? (1921), 73.
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It took Galileo 16 years to master the universe. You have one night. It seems unfair. The genius had all that time. While you have a few short hours to learn sun spots from your satellites before the dreaded astronomy exam. If Galileo had used Vivarin [caffeine tablets], maybe he could have mastered the solar system faster, too.
Advertisement for Vivarin in student newspaper.
Daily Philadelphian, 6 Dec 1990. Quotation noted by W. H. Brock.
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It seems to me that your Reverence and Signor Galileo act prudently when you content yourselves with speaking hypothetically and not absolutely, as I have always understood that Copernicus spoke. To say that on the supposition of the Earth's movement and the Sun's quiescence all the celestial appearances are explained better than by the theory of eccentrics and epicycles is to speak with excellent good sense and to run no risk whatsoever. Such a manner of speaking is enough for a mathematician. But to want to affirm that the Sun, in very truth, is at the center of the universe and only rotates on its axis without going from east to west, is a very dangerous attitude and one calculated not only to arouse all Scholastic philosophers and theologians but also to injure our holy faith by contradicting the Scriptures.
Letter to Paolo Antonio Foscarini, 12 April 1615. Quoted in Giorgio De Santillana, The Crime of Galileo (1955), 99.
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It is a vulgar belief that our astronomical knowledge dates only from the recent century when it was rescued from the monks who imprisoned Galileo; but Hipparchus … who among other achievements discovered the precession of the eqinoxes, ranks with the Newtons and the Keplers; and Copernicus, the modern father of our celestial science, avows himself, in his famous work, as only the champion of Pythagoras, whose system he enforces and illustrates. Even the most modish schemes of the day on the origin of things, which captivate as much by their novelty as their truth, may find their precursors in ancient sages, and after a careful analysis of the blended elements of imagination and induction which charaterise the new theories, they will be found mainly to rest on the atom of Epicurus and the monad of Thales. Scientific, like spiritual truth, has ever from the beginning been descending from heaven to man.
Lothair (1879), preface, xvii.
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The strangest thing of all is that our ulama these days have divided science into two parts. One they call Muslim science, and one European science. Because of this they forbid others to teach some of the useful sciences. They have not understood that science is that noble thing that has no connection with any nation, and is not distinguished by anything but itself. Rather, everything that is known is known by science, and every nation that becomes renowned becomes renowned through science. Men must be related to science, not science to men. How very strange it is that the Muslims study those sciences that are ascribed to Aristotle with the greatest delight, as if Aristotle were one of the pillars of the Muslims. However, if the discussion relates to Galileo, Newton, and Kepler, they consider them infidels. The father and mother of science is proof, and proof is neither Aristotle nor Galileo. The truth is where there is proof, and those who forbid science and knowledge in the belief that they are safeguarding the Islamic religion are really the enemies of that religion. Lecture on Teaching and Learning (1882).
In Nikki R. Keddie, An Islamic Response to Imperialism (1983), 107.
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When Galileo caused balls, the weights of which he had himself previously determined, to roll down an inclined plane; when Torricelli made the air carry a weight which he had calculated beforehand to be equal to that of a definite volume of water; or in more recent times, when Stahl changed metal into lime, and lime back into metal, by withdrawing something and then restoring it, a light broke upon all students of nature. They learned that reason has insight only into that which it produces after a plan of its own, and that it must not allow itself to be kept, as it were, in nature's leading-strings, but must itself show the way with principles of judgement based upon fixed laws, constraining nature to give answer to questions of reason's own determining. Accidental observations, made in obedience to no previously thought-out plan, can never be made to yield a necessary law, which alone reason is concerned to discover.
Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929), 20.
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Repudiating the sensible world, which he neither sees himself nor believes from those who have, the Peripatetic joins combat by childish quibbling in a world on paper, and denies the Sun shines because he himself is blind.
Letter to Galileo Galilei (28 Mar 1611). Johannes Kepler Gesammelte Werke (1937- ), Vol. 16, letter 611, 1. 17-20, p. 372.
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The stone that Dr. Johnson once kicked to demonstrate the reality of matter has become dissipated in a diffuse distribution of mathematical probabilities. The ladder that Descartes, Galileo, Newton, and Leibniz erected in order to scale the heavens rests upon a continually shifting, unstable foundation.
Mathematics in Western Culture (1953), 382.
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What the founders of modern science, among them Galileo, had to do, was not to criticize and to combat certain faulty theories, and to correct or to replace them by better ones. They had to do something quite different. They had to destroy one world and to replace it by another. They had to reshape the framework of our intellect itself, to restate and to reform its concepts, to evolve a new approach to Being, a new concept of knowledge, a new concept of science—and even to replace a pretty natural approach, that of common sense, by another which is not natural at all.
Galileo and Plato (1943), 405.
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The faith of scientists in the power and truth of mathematics is so implicit that their work has gradually become less and less observation, and more and more calculation. The promiscuous collection and tabulation of data have given way to a process of assigning possible meanings, merely supposed real entities, to mathematical terms, working out the logical results, and then staging certain crucial experiments to check the hypothesis against the actual empirical results. But the facts which are accepted by virtue of these tests are not actually observed at all. With the advance of mathematical technique in physics, the tangible results of experiment have become less and less spectacular; on the other hand, their significance has grown in inverse proportion. The men in the laboratory have departed so far from the old forms of experimentation—typified by Galileo's weights and Franklin's kite—that they cannot be said to observe the actual objects of their curiosity at all; instead, they are watching index needles, revolving drums, and sensitive plates. No psychology of 'association' of sense-experiences can relate these data to the objects they signify, for in most cases the objects have never been experienced. Observation has become almost entirely indirect; and readings take the place of genuine witness.
Philosophy in a New Key; A Study in Inverse the Symbolism of Reason, Rite, and Art (1942), 19-20.
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[W]hen Galileo discovered he could use the tools of mathematics and mechanics to understand the motion of celestial bodies, he felt, in the words of one imminent researcher, that he had learned the language in which God recreated the universe. Today we are learning the language in which God created life. We are gaining ever more awe for the complexity, the beauty, the wonder of God's most devine and sacred gift.
From White House Announcement of the Completion of the First Survey of the Entire Human Genome Project, broadcast on the day of the publication of the first draft of the human genome. Quoted in transcript on the National Archives, Clinton White House web site, 'Text of Remarks on the Completion of the First Survey of the Entire Human Genome Project' (26 Jun 2000).
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[Newton wrote to Halley … that he would not give Hooke any credit] That, alas, is vanity. You find it in so many scientists. You know, it has always hurt me to think that Galileo did not acknowledge the work of Kepler.
In I. Bernard Cohen, 'An Interview with Einstein', in Anthony Philip French (ed.), Einstein: A Centenary Volume (1979), 41. Cited in Timothy Ferris, Coming of Age in the Milky Way (2003), 94-95.
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For the pre-Darwinian age had come to be regarded as a Dark Age in which men still believed that the book of Genesis was a standard scientific treatise, and that the only additions to it were Galileo'a demonstration of Leonardo da Vinci's simple remark that the earth is a moon of the sun, Sir Humphrey Davy's invention of the safety lamp, the discovery of electricity, the application of steam to industrial purposes, and the penny post.
Back to Methuselah: A Metabiological Pentateuch‎ (1921), viii.
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What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth.
A History of Western Philosophy (1945), 725.
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Anthropology found its Galileo in Rivers, its Newton in Mauss.
Structural Anthropology (1958), 159.
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It is impossible not to feel stirred at the thought of the emotions of man at certain historic moments of adventure and discovery—Columbus when he first saw the Western shore, Pizarro when he stared at the Pacific Ocean, Franklin when the electric spark came from the string of his kite, Galileo when he first turned his telescope to the heavens. Such moments are also granted to students in the abstract regions of thought, and high among them must be placed the morning when Descartes lay in bed and invented the method of co-ordinate geometry.
Quoted in James Roy Newman, The World of Mathematics (2000), Vol. 1, 239.
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By night the Glass
Of Galileo ... observes
Imagin'd Land and Regions in the Moon.
Paradise Lost, Book 5, lines 261-263. In Books V and VI, edited by A. W. Verity,(1910), 11.
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There it was that I found and visited the famous Galileo, grown old, a prisner to the inquisition, for thinking in astronomy otherwise than the Franciscan and Dominican licencers thought.
Recounting the tyranny of the inquisition that Milton had seen for himself in Italy. When he visited in 1640, he was age 30, and Galileo was age 77 and nearly blind.
'Proof.—The servile condition of learning in Italy, the home of licencing.' Areopagitica; A Speech of Mr John Milton to the Parlament of England (24 Nov 1644), editted by Edward Arber (1868), 60.
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When young Galileo, then a student at Pisa, noticed one day during divine service a chandelier swinging backwards and forwards, and convinced himself, by counting his pulse, that the duration of the oscillations was independent of the arc through which it moved, who could know that this discovery would eventually put it in our power, by means of the pendulum, to attain an accuracy in the measurement of time till then deemed impossible, and would enable the storm-tossed seaman in the most distant oceans to determine in what degree of longitude he was sailing?
Hermann von Helmholtz, Edmund Atkinson (trans.), Popular Lectures on Scientific Subjects: First Series (1883), 29.
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History of science is a relay race, my painter friend. Copernicus took over his flag from Aristarchus, from Cicero, from Plutarch; and Galileo took that flag over from Copernicus.
From the play Galileo Galilei (2001) .
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It is better to go near the truth and be imprisoned than to stay with the wrong and roam about freely, master Galilei. In fact, getting attached to falsity is terrible slavery, and real freedom is only next to the right.
From the play Galileo Galilei (2001) .
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The way in which the persecution of Galileo has been remembered is a tribute to the quiet commencement of the most intimate change in outlook which the human race had yet encountered. Since a babe was born in a manger, it may be doubted whether so great a thing has happened with so little stir
In Science and the Modern World (1925), 2.
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After a duration of a thousand years, the power of astrology broke down when, with Copernicus, Kepler, and Galileo, the progress of astronomy overthrew the false hypothesis upon which the entire structure rested, namely the geocentric system of the universe. The fact that the earth revolves in space intervened to upset the complicated play of planetary influences, and the silent stars, related to the unfathomable depths of the sky, no longer made their prophetic voices audible to mankind. Celestial mechanics and spectrum analysis finally robbed them of their mysterious prestige.
Franz Cumont, translated by J.B. Baker, Astrology and Religion Among the Greeks and Romans (1912, 2007), 6.
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He scarce had ceased when the superior fiend
Was moving toward the shore; his ponderous shield
Ethereal temper, massy, large and round,
Behind him cast; the broad circumference
Hung on his shoulders like the moon, whose orb
Through optic glass the Tuscan artist views
At evening from the top of Fésolè,
Or in Valdarno, to descry new lands,
Rivers or mountains in her spotty globe.
Paradise Lost, Books I and II (1667), edited by Anna Baldwin (1998), lines 283-91, p. 9.
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One can truly say that the irresistible progress of natural science since the time of Galileo has made its first halt before the study of the higher parts of the brain, the organ of the most complicated relations of the animal to the external world. And it seems, and not without reason, that now is the really critical moment for natural science; for the brain, in its highest complexity—the human brain—which created and creates natural science, itself becomes the object of this science.
Natural Science and Brain (1909), 120.
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The pre-Darwinian age had come to be regarded as a Dark Age in which men still believed that the book of Genesis was a standard scientific treatise, and that the only additions to it were Galileo's demonstration of Leonardo da Vinci's simple remark that the earth is a moon of the sun, Newton's theory of gravitation, Sir Humphry Davy's invention of the safety-lamp, the discovery of electricity, the application of steam to industrial purposes, and the penny post.
Back to Methuselah: a Metabiological Pentateuch (1921), viii.
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A man does not attain the status of Galileo merely because he is persecuted; he must also be right.
In essay 'Velikovsky in Collision', Natural History (Mar 1975), collected in Ever Since Darwin: Reflections in Natural History (1977, 1992), 154.
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I sometimes think about the tower at Pisa as the first particle accelerator, a (nearly) vertical linear accelerator that Galileo used in his studies.
In Leon Lederman and Dick Teresi, The God Particle: If the Universe is the Answer, What is the Question (1993, 2006), 200.
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It is in the name of Moses that Bellarmin thunderstrikes Galileo; and this great vulgarizer of the great seeker Copernicus, Galileo, the old man of truth, the magian of the heavens, was reduced to repeating on his knees word for word after the inquisitor this formula of shame: “Corde sincera et fide non ficta abjuro maledico et detestor supradictos errores et hereses.” Falsehood put an ass's hood on science.
[With a sincere heart, and of faith unfeigned, I deny by oath, condemn and detest the aforesaid errors and heresies.]
In Victor Hugo and Lorenzo O'Rourke (trans.) Victor Hugo's Intellectual Autobiography: (Postscriptum de ma vie) (1907), 313.
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How fortunate for civilization, that Beethoven, Michelangelo, Galileo and Faraday were not required by law to attend schools where their total personalities would have been operated upon to make them learn acceptable ways of participating as members of “the group.”
In speech, 'Education for Creativity in the Sciences', Conference at New York University, Washington Square. As quoted by Gene Currivan in 'I.Q. Tests Called Harmful to Pupil', New York Times (16 Jun 1963), 66.
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See also:
  • todayinsci icon 15 Feb - short biography, births, deaths and events on date of Galilei's birth.
  • todayinsci icon Galileo Galilei - Quotations - Abjuration
  • todayinsci icon Galileo Gailei - biography from Famous Men of Science (1889).
  • todayinsci icon Galileo - “And Yet It Moves” illustrated quote - Medium 500px
  • todayinsci icon Galileo - “And Yet It Moves” illustrated quote - Large 800px
  • book icon Galileo: A Life, by James Reston. - book suggestion.
  • booklist icon Booklist for Galileo Galilei.

Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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- 100 -
Sophie Germain
Gertrude Elion
Ernest Rutherford
James Chadwick
Marcel Proust
William Harvey
Johann Goethe
John Keynes
Carl Gauss
Paul Feyerabend
- 90 -
Antoine Lavoisier
Lise Meitner
Charles Babbage
Ibn Khaldun
Euclid
Ralph Emerson
Robert Bunsen
Frederick Banting
Andre Ampere
Winston Churchill
- 80 -
John Locke
Bronislaw Malinowski
Bible
Thomas Huxley
Alessandro Volta
Erwin Schrodinger
Wilhelm Roentgen
Louis Pasteur
Bertrand Russell
Jean Lamarck
- 70 -
Samuel Morse
John Wheeler
Nicolaus Copernicus
Robert Fulton
Pierre Laplace
Humphry Davy
Thomas Edison
Lord Kelvin
Theodore Roosevelt
Carolus Linnaeus
- 60 -
Francis Galton
Linus Pauling
Immanuel Kant
Martin Fischer
Robert Boyle
Karl Popper
Paul Dirac
Avicenna
James Watson
William Shakespeare
- 50 -
Stephen Hawking
Niels Bohr
Nikola Tesla
Rachel Carson
Max Planck
Henry Adams
Richard Dawkins
Werner Heisenberg
Alfred Wegener
John Dalton
- 40 -
Pierre Fermat
Edward Wilson
Johannes Kepler
Gustave Eiffel
Giordano Bruno
JJ Thomson
Thomas Kuhn
Leonardo DaVinci
Archimedes
David Hume
- 30 -
Andreas Vesalius
Rudolf Virchow
Richard Feynman
James Hutton
Alexander Fleming
Emile Durkheim
Benjamin Franklin
Robert Oppenheimer
Robert Hooke
Charles Kettering
- 20 -
Carl Sagan
James Maxwell
Marie Curie
Rene Descartes
Francis Crick
Hippocrates
Michael Faraday
Srinivasa Ramanujan
Francis Bacon
Galileo Galilei
- 10 -
Aristotle
John Watson
Rosalind Franklin
Michio Kaku
Isaac Asimov
Charles Darwin
Sigmund Freud
Albert Einstein
Florence Nightingale
Isaac Newton