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Galileo Galilei

53 quotes

“Quòd tertio loca à nobis fuit obſeruatum, eſt ipſiuſmet LACTEI Circuli eſſentia, ſeu materies, quam Perſpicilli beneficio adeò ad ſenſum licet intueri, vt & altercationes omnes, quæ per tot ſæcula Philoſophos excrucia runt ab oculata certitudine dirimantur, nosque à verboſis dſputationibus liberemur.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Revealing great, unusual, and remarkable spectacles, opening these to the consideration of every man, and especially of philosophers and astronomers; as observed by Galileo Galilei, Gentleman of Florence, Professor of Mathematics in the University of Padua, with the aid of a spyglass lately invented by him, in the surface of the Moon, in innumerable fixed stars, in nebulae, and above all in four planets swiftly revolving about Jupiter at differing distances and periods, and known to no one before the author recently perceived them and decided they should be named the Medicean Stars”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Translation by Stillman Drake in Discoveries and Opinions of Galileo (1957)
“Surely it is a great thing to increase the numerous host of fixed stars previously visible to the unaided vision, adding countless more which have never before been seen, exposing these plainly to the eye in numbers ten times exceeding the old and familiar stars.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Translation by Stillman Drake in Discoveries and Opinions of Galileo (1957)
“It seems to me that it was well said by Madama Serenissima, and insisted on by your reverence, that the Holy Scripture cannot err, and that the decrees therein contained are absolutely true and inviolable. But I should have in your place added that, though Scripture cannot err, its expounders and interpreters are liable to err in many ways; and one error in particular would be most grave and most frequent, if we always stopped short at the literal signification of the words.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“To this end they make a shield of their hypocritical zeal for religion. They go about invoking the Bible, which they would have minister to their deceitful purposes. Contrary to the sense of the Bible and the intention of the holy Fathers, if I am not mistaken, they would extend such authorities until even in purely physical matters — where faith is not involved — they would have us altogether abandon reason and the evidence of our senses in favor of some biblical passage, though under the surface meaning of its words this passage may contain a different sense.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Copernicus never discusses matters of religion or faith, nor does he use argument that depend in any way upon the authority of sacred writings which he might have interpreted erroneously. ... He did not ignore the Bible, but he knew very well that if his doctrine were proved, then it could not contradict the Scriptures when they were rightly understood.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I do not feel obliged to believe that the same God who has endowed us with senses, reason, and intellect has intended us to forgo their use and by some other means to give us knowledge which we can attain by them.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I would say here something that was heard from an ecclesiastic of the most eminent degree [probably Caesar Baronius]: "The intention of the Holy Ghost is to teach us how one goes to heaven, not how heaven goes.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Philosophy is written in this grand book, which stands continually open before our eyes (I say the 'Universe'), but can not be understood without first learning to comprehend the language and know the characters as it is written. It is written in mathematical language, and its characters are triangles, circles and other geometric figures, without which it is impossible to humanly understand a word; without these one is wandering in a dark labyrinth.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: As translated in The Metaphysical Foundations of Modern Physical Science (1925) by Edwin Arthur Burtt, p. 64
“Whence do you have it that the terrestrial globe is so heavy? For my part, either I do not know what heaviness is, or the terrestrial globe is neither heavy nor light, as likewise all other globes of the universe. Heaviness to me (and I believe to Nature) is that innate tendency by which a body resists being moved from its natural place and by which, when forcibly removed therefrom, it spontaneously returns there. Thus a bucketful of water raised on high and set free, returns to the sea; but who will say that the same water remains heavy in the sea, when being set free there, does not move?”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“To apply oneself to great inventions, starting from the smallest beginnings, is no task for ordinary minds; to divine that wonderful arts lie hid behind trivial and childish things is a conception for superhuman talents.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“If you could see the earth illuminated when you were in a place as dark as night, it would look to you more splendid than the moon.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Among all the great men who have philosophized about this remarkable effect, I am more astonished at Kepler than at any other. Despite his open and acute mind, and though he has at his fingertips the motions attributed to the earth, he nevertheless lent his ear and his assent to the moon's dominion over the waters, to occult properties, and to such puerilities.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“The sun, with all those planets revolving around it and dependent on it, can still ripen a bunch of grapes as if it had nothing else in the universe to do.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Of such are the mathematical sciences alone; that is, geometry and arithmetic, in which the Divine intellect indeed knows infinitely more propositions, since it knows all. But with regard to those few which the human intellect does understand, I believe its knowledge equals the Divine in objective certainty, for here it succeeds in understanding necessity, beyond which there can be no greater sureness.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: In the 1661 translation by Thomas Salusbury: … such are the pure Mathematical sciences, to wit, Geometry and Arithmetick: in which Divine Wisdom knows infinite more propositions, because it knows them all; but I believe…
“I cannot sufficiently admire the eminence of those men's wits, that have received and held it to be true, and with the sprightliness of their judgments offered such violence to their own senses, as that they have been able to prefer that which their reason dictated to them, to that which sensible experiments represented most manifestly to the contrary. ...I cannot find any bounds for my admiration, how that reason was able in Aristarchus and Copernicus, to commit such a rape on their senses, as in despite thereof to make herself mistress of their credulity.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Thomas Salusbury translation (1661) p. 301 as quoted by Edwin Arthur Burtt, The Metaphysical Foundations of Modern Physical Science (1925)
“After the publication of my dialogues, I was summoned to Rome by the Congregation of the holy Office, where, being arrived on the 10th of February 1633, I was subjected to the infinite clemency of that tribunal, and of the Sovereign Pontiff, Urban the Eighth; who, notwithstanding, thought me deserving of his esteem.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I am certainly interested in a tribunal in which, for having used my reason, I was deemed little less than a heretic. Who knows but men will reduce me from the profession of a philosopher to that of historian of the Inquisition! But they behave to me in order that I may become the ignoramus and the fool of Italy...”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Well, since paradoxes are at hand, let us see how it might be demonstrated that in a finite continuous extension it is not impossible for infinitely many voids to be found.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Salviati, First Day, Stillman Drake translation (1974)
“I am quite convinced; and, believe me, if I were again beginning my studies, I should follow the advice of Plato and start with mathematics, a science which proceeds very cautiously and admits nothing as established until it has been rigidly demonstrated.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“It has been observed that missiles and projectiles describe a curved path of some sort; however no one has pointed out the fact that this path is a parabola. But this and other facts, not few in number or less worth knowing, I have succeeded in proving; and what I consider more important, there have been opened up to this vast and most excellent science, of which my work is merely the beginning, ways and means by which other minds more acute than mine will explore its remote corners.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“This [experimentation] is the custom—and properly so—in those sciences where mathematical demonstrations are applied to natural phenomena, as is seen in the case of perspective, astronomy, mechanics, music, and others where the principles, once established by well-chosen experiments, become the foundations of the entire superstructure.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“See now the power of truth; the same experiment which at first glance seemed to show one thing, when more carefully examined, assures us of the contrary.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I mentally conceive of some moveable [sphere] projected on a horizontal plane, all impediments being put aside. Now it is evident... that equable motion on this plane would be perpetual if the plane were of infinite extent, but if we assume it to be ended, and [situated] on high, the movable, driven to the end of this plane and going on further, adds on to its previous equable and indelible motion, that downward tendency which it has from its heaviness. Thus, there emerges a certain motion, compounded...”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Author, Day Four, On the Motion of Projectiles, Stillman Drake translation (1974) p. 268
“Proposition I. Theorem I: When a projectile is carried in motion compounded from equable horizontal and from naturally accelerated downward [motions], it describes a semiparabolic line in its movement.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Author, Day Four, Stillman Drake translation (1974) p. 269
“The speed of the ball—thanks to opposition from the air—will not go on increasing forever. Rather, what will happen is seen in bodies of very little weight falling through no great distance; I mean, a reduction to equable motion, which will occur also in a lead or iron ball after the descent of some thousands of braccia. This bounded terminal speed will be called the maximum that such a heavy body can naturally attain through the air...”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Salviati, Day Four, 278-279 Stillman Drake translation (1974)
“If I shall have sufficient strength to improve and amplify what was written and published by me up to now about motion by adding some little speculations, and in particular those relating to the force of percussion, in the investigation of which I have consumed hundreds and thousands of hours, and finally reduced this to very easy explanation, so that people can understand it in less than half an hour of time.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“What has philosophy got to do with measuring anything? It's the mathematicians you have to trust, and they measure the skies like we measure a field.”
Galileo Galilei (1564–1642) first seen 1606 wikiquote, CC BY-SA 4.0 source
Recorded in: Matteo" in Concerning the New Star (1606)
“My dear Kepler, what would you say of the learned here, who, replete with the pertinacity of the asp, have steadfastly refused to cast a glance through the telescope? What shall we make of this? Shall we laugh, or shall we cry?”
Galileo Galilei (1564–1642) first seen 1610 wikiquote, CC BY-SA 4.0 source
Recorded in: Letter to Johannes Kepler (1610), as quoted in The Crime of Galileo (1955) by Giorgio De Santillana
“sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo, sì perché le presenti osservazioni spogliano d'autorità i decreti de' passati scrittori, i quali se vedute l'avessero, avrebbono diversamente determinato.”
Galileo Galilei (1564–1642) first seen 1558 wikiquote, CC BY-SA 4.0 source
Recorded in: Third letter on sunspots (December 1612) to Mark Wesler (1558 - 1614), as quoted in Discoveries and Opinions of Galileo (1957) by Stillman Drake, p. 134 - 135; Italian text online at Liber Liber, also from IntraText.
“We seek not what God could have done but what He has done.… God could have caused birds to fly with bones of solid gold, with veins full of quicksilver, with flesh heavier than lead and very small and heavy wings, so as to better show His power … but He wanted to make their bones, flesh and feathers very light … to teach us that He likes simplicity and ease.”
Galileo Galilei (1564–1642) first seen 1631 wikiquote, CC BY-SA 4.0 source
Recorded in: Notes in a copy of Jean-Baptiste Morin's "Famous and ancient problems of the earth's motion or rest, yet to be solved" (published 1631). Some English sources incorrectly attribute this to the Dialogue, concluding it (al…
“I have been in my bed for five weeks, oppressed with weakness and other infirmities from which my age, seventy four years, permits me not to hope release. Added to this (proh dolor! [O misery!]) the sight of my right eye — that eye whose labors (dare I say it) have had such glorious results — is for ever lost. That of the left, which was and is imperfect, is rendered null by continual weeping.”
Galileo Galilei (1564–1642) first seen 1637 wikiquote, CC BY-SA 4.0 source
Recorded in: Letter to Élie Diodati (4 July 1637), as translated in The Private Life of Galileo: Compiled primarily from his correspondence and that of his eldest daughter, Sister Maria Celeste (1870) by Mary Allan-Olney, p. 278
“Alas! Your dear friend and servant Galileo has been for the last month hopelessly blind; so that this heaven, this earth, this universe, which I by my marvelous discoveries and clear demonstrations had enlarged a hundred thousand times beyond the belief of the wise men of bygone ages, henceforward for me is shrunk into such a small space as is filled by my own bodily sensations.”
Galileo Galilei (1564–1642) first seen 1638 wikiquote, CC BY-SA 4.0 source
Recorded in: Letter to Élie Diodati (2 January 1638), as translated in The Private Life of Galileo: Compiled primarily from his correspondence and that of his eldest daughter, Sister Maria Celeste (1870) by Mary Allan-Olney, p. 279
“Wine is a mixture of moisture and light.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: As quoted in Lorenzo Magalotti's Scientific and Scholarly Letter (1721)
“Names and attributes must be accommodated to the essence of things, and not the essence to the names, since things come first and names afterwards.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: As quoted in Discoveries and Opinions of Galileo (1957) by Stillman Drake, p. 92
“Quòd tertio loca à nobis fuit obſeruatum, eſt ipſiuſmet LACTEI Circuli eſſentia, ſeu materies, quam Perſpicilli beneficio adeò ad ſenſum licet intueri, vt & altercationes omnes, quæ per tot ſæcula Philoſophos excrucia runt ab oculata certitudine dirimantur, nosque à verboſis dſputationibus liberemur.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Original text as reproduced in Edward Tufte, Beautiful Evidence (Cheshire, Connecticut: Graphics Press LLC, 2006), 101 (p. 3 of 4, insert between pp. 16V & 17R. Original manuscript renders the "q" in "nosque" with acute…
“About ten months ago a report reached my ears that a certain Fleming 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 the truly remarkable effect several experiences were related, to which some persons gave credence while others denied them. A few days later a report was confirmed to me in a letter from a noble Frenchman in Paris, Jacques Badovere, which caused me to apply myself wholeheartedly to inquire into 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 I fitted two glass lenses, both plane on one side while on the other side one was spherically convex and the other concave. Then placing my eye near the concave lens I perceived objects satisfactorily large and near, for they appeared three times closer and nine times larger than when seen with the naked eye alone. Next I constructed another one, more accurate, which represented objects as enlarged more than sixty times. Finally, sparing neither labor nor expense, I succeeded in constructing for myself so excellent an instrument that objects seen by means of it appeared nearly one thousand times larger and over thirty times closer than when regarded with our natural vision.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: Translation by Stillman Drake in Discoveries and Opinions of Galileo (1957)
“Some years ago, as Your Serene Highness well knows, I discovered in the heavens many things that had not been seen before our own age. The novelty of these things, as well as some consequences which followed from them in contradiction to the physical notions commonly held among academic philosophers, stirred up against me no small number of professors — as if I had placed these things in the sky with my own hands in order to upset nature and overturn the sciences. They seemed to forget that the increase of known truths stimulates the investigation, establishment, and growth of the arts; not their diminution or destruction.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“The passage of time has revealed to everyone the truths that I previously set forth; and, together with the truth of the facts, there has come to light the great difference in attitude between those who simply and dispassionately refused to admit the discoveries to be true, and those who combined with their incredulity some reckless passion of their own. Men who were well grounded in astronomical and physical science were persuaded as soon as they received my first message. There were others who denied them or remained in doubt only because of their novel and unexpected character, and because they had not yet had the opportunity to see for themselves. These men have by degrees come to be satisfied. But some, besides allegiance to their original error, possess I know not what fanciful interest in remaining hostile not so much toward the things in question as toward their discoverer. No longer being able to deny them, these men now take refuge in obstinate silence, but being more than ever exasperated by that which has pacified and quieted other men, they divert their thoughts to other fancies and seek new ways to damage me.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Persisting in their original resolve to destroy me and everything mine by any means they can think of, these men are aware of my views in astronomy and philosophy. They know that as to the arrangement of the parts of the universe, I hold the sun to be situated motionless in the center of the revolution of the celestial orbs while the earth revolves about the sun. They know also that I support this position not only by refuting the arguments of Ptolemy and Aristotle, but by producing many counter-arguments; in particular, some which relate to physical effects whose causes can perhaps be assigned in no other way. In addition there are astronomical arguments derived from many things in my new celestial discoveries that plainly confute the Ptolemaic system while admirably agreeing with and confirming the contrary hypothesis.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Nature … 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. For the Bible is not chained in every expression to conditions as strict as those which govern all physical effects; nor is God any less excellently revealed in Nature's actions than in the sacred statements of the Bible.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I tell you that if natural bodies have it from Nature to be moved by any movement, this can only be circular motion, nor is it possible that Nature has given to any of its integral bodies a propensity to be moved by straight motion. I have many confirmations of this proposition, but for the present one alone suffices, which is this. I suppose the parts of the universe to be in the best arrangement, so that none is out of its place, which is to say that Nature and God have perfectly arranged their structure. This being so, it is impossible for those parts to have it from Nature to be moved in straight, or in other than circular motion, because what moves straight changes place, and if it changes place naturally, then it was at first in a place preternatural to it, which goes against the supposition. Therefore, if the parts of the world are well ordered, straight motion is superfluous and not natural, and they can only have it when some body is forcibly removed from its natural place, to which it would then return by a straight line, for thus it appears that a part of the earth does [move] when separated from its whole. I said "it appears to us," because I am not against thinking that not even for such an effect does Nature make use of straight line motion.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: A note on this statement is included by Stillman Drake in his Galileo at Work, His Scientific Biography (1981): Galileo adhered to this position in his Dialogue at least as to the "integral bodies of the universe." by w…
“It always seems to me extreme rashness on the part of some when they want to make human abilities the measure of what nature can do. On the contrary, there is not a single effect in nature, even the least that exists, such that the most ingenious theorists can arrive at a complete understanding of it. This vain presumption of understanding everything can have no other basis than never understanding anything. For anyone who had experienced just once the perfect understanding of one single thing, and had truly tasted how knowledge is accomplished, would recognize that of the infinity of other truths he understands nothing.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I cannot without great astonishment — I might say without great insult to my intelligence — hear it attributed as a prime perfection and nobility of the natural and integral bodies of the universe that they are invariant, immutable, inalterable, etc., while on the other hand it is called a great imperfection to be alterable, generable, mutable, etc. For my part I consider the earth very noble and admirable precisely because of the diverse alterations, changes, generations, etc. that occur in it incessantly. If, not being subject to any changes, it were a vast desert of sand or a mountain of jasper, or if at the time of the flood the waters which covered it had frozen, and it had remained an enormous globe of ice where nothing was ever born or ever altered or changed, I should deem it a useless lump in the universe, devoid of activity and, in a word, superfluous and essentially non-existent. This is exactly the difference between a living animal and a dead one; and I say the same of the moon, of Jupiter, and of all other world globes. The deeper I go in considering the vanities of popular reasoning, the lighter and more foolish I find them. What greater stupidity can be imagined than that of calling jewels, silver, and gold "precious," and earth and soil "base"? People who do this ought to remember that if there were as great a scarcity of soil as of jewels or precious metals, there would not be a prince who would not spend a bushel of diamonds and rubies and a cartload of gold just to have enough earth to plant a jasmine in a little pot, or to sow an orange seed and watch it sprout, grow, and produce its handsome leaves, its fragrant flowers, and fine fruit. It is scarcity and plenty that make the vulgar take things to be precious or worthless; they call a diamond very beautiful because it is like pure water, and then would not exchange one for ten barrels of water. Those who so greatly exalt incorruptibility, inalterability, etc. are reduced to talking this way, I believe, by their great desire to go on living, and by the terror they have of death. They do not reflect that if men were immortal, they themselves would never have come into the world. Such men really deserve to encounter a Medusa's head which would transmute them into statues of jasper or of diamond, and thus make them more perfect than they are.”
Galileo Galilei (1564–1642) first seen 1190 wikiquote, CC BY-SA 4.0 source
Recorded in: Compare Maimonides "If man were never subject to change there could be no generation; there would be one single being..." Guide for the Perplexed (c. 1190)
“If what we are discussing were a point of law or of the humanities, in which neither true nor false exists, one might trust in subtlety of mind and readiness of tongue and in the greater experience of the writers, and expect him who excelled in those things to make his reasoning most plausible, and one might judge it to be the best. But in the natural sciences, whose conclusions are true and necessary and have nothing to do with human will, one must take care not to place oneself in the defense of error; for here a thousand Demostheneses and a thousand Aristotles would be left in the lurch by every mediocre wit who happened to hit upon the truth for himself. Therefore, Simplicio, give up this idea and this hope of yours that there may be men so much more learned, erudite, and well-read than the rest of us as to be able to make that which is false become true in defiance of nature.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“In the long run my observations have convinced me that some men, reasoning preposterously, first establish some conclusion in their minds which, either because of its being their own or because of their having received it from some person who has their entire confidence, impresses them so deeply that one finds it impossible ever to get it out of their heads. Such arguments in support of their fixed idea as they hit upon themselves or hear set forth by others, no matter how simple and stupid these may be, gain their instant acceptance and applause. On the other hand whatever is brought forward against it, however ingenious and conclusive, they receive with disdain or with hot rage — if indeed it does not make them ill. Beside themselves with passion, some of them would not be backward even about scheming to suppress and silence their adversaries.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“I was obliged to retract, like a good Catholic, this opinion of mine; and as a punishment my dialogue was prohibited; and after five months being dismissed from Rome (at the time that the city of Florence was infected with plague), the habitation which with generous pity was assigned to me, was that of the dearest friend I had in Siena, Monsignor the Archbishop Piccolomini, whose most agreeable conversation I enjoyed with such quite and satisfaction of mind, that having there resumed my studies, I discovered and demonstrated a great number on the mechanical conclusions on the resistance of solids … after about five months, the pestilence having ceased, the confinement of that house was changed by His Holiness for the freedom of the country so agreeable to me, whence I returned to the villa of Bellosguardo, and afterwards to Arcetri, where I still breathe salubrious air near my dear native-country Florence. Stay sane.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“My purpose is to set forth a very new science dealing with a very ancient subject. There is, in nature, perhaps nothing older than motion, concerning which the books written by philosophers are neither few nor small; nevertheless I have discovered by experiment some properties of it which are worth knowing and which have not hitherto been either observed or demonstrated. Some superficial observations have been made, as, for instance, that the free motion [naturalem motum] of a heavy falling body is continuously accelerated; but to just what extent this acceleration occurs has not yet been announced; for so far as I know, no one has yet pointed out that the distances traversed, during equal intervals of time, by a body falling from rest, stand to one another in the same ratio as the odd numbers beginning with unity.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“Indeed, I think we may concede to our Academician, without flattery, his claim that in the principle [principio, i. e., accelerated motion] laid down in this treatise he has established a new science dealing with a very old subject. Observing with what ease and clearness he deduces from a single principle the proofs of so many theorems, I wonder not a little how such a question escaped the attention of Archimedes, Apollonius, Euclid and so many other mathematicians and illustrious philosophers, especially since so many ponderous tomes have been devoted to the subject of motion. (Galileo referred to himself as the/our Academician in his dialogue)”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
“It seems to me proper to adorn the Author's thought here with its conformity to a conception of Plato's regarding the determination of the various speeds of equable motion in the celestial motions of revolution. ...he said that God, after having created the movable celestial bodies, in order to assign to them those speeds with which they must be moved perpetually in equable circular motion, made them depart from rest and move through determinate spaces in that natural straight motion in which we sensibly see our moveables to be moved from the state of rest, successively accelerating. And he added that these having been made to gain that degree [of speed] which it pleased God that they should maintain forever, He turned their straight motion into circulation, the only kind [of motion] that is suitable to be conserved equably, turning always without retreat from or approach toward any pre-established goal desired by them. The conception is truly worthy of Plato, and it is to be more esteemed to the extent that its foundations, of which Plato remained silent, but which were discovered by our Author in removing their poetical mask or semblance, show it the guise of a true story.”
Galileo Galilei (1564–1642) said by 1642 at the latest wikiquote, CC BY-SA 4.0 source
Recorded in: I. Bernard Cohen's thesis: Galileo believed only circular (not straight line) motion may be conserved (perpetual), see The New Birth of Physics (1960).