Galileo Galilei Quotes

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

There are those who reason well, but they are greatly outnumbered by those who reason badly. ~ Galileo Galilei

Surely, God could have caused birds to fly with their bones made of solid gold, with their veins full of quicksilver, with their flesh heavier than lead, and with their wings exceedingly small. He did not, and that ought to show something. It is only in order to shield your ignorance that you put the Lord at every turn to the refuge of a miracle. ~ Galileo Galilei

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

I, Galileo, son of the late Vicenzo Galilei, swear that I never said that the prime numbers are useless. What I said was that you cannot count lunar craters by counting 2, 3, 5, 7 ... ~ Galileo Galilei

We come astonishingly close to the mystical beliefs of Pythagoras and his followers who attempted to submit all of life to the sovereignty of numbers. Many of our psychologists, sociologists, economists and other latter-day cabalists will have numbers to tell them the truth or they will have nothing ... We must remember that Galileo merely said that the language of nature is written in mathematics. He did not say that everything is. And even the truth about nature need not be expressed in mathematics. For most of human history, the language of nature has been the language of myth and ritual. These forms, one might add, had the virtues of leaving nature unthreatened and of encouraging the belief that human beings are part of it. It hardly befits a people who stand ready to blow up the planet to praise themselves too vigorously for having found the true way to talk about nature. ~ Neil Postman

In the sciences, the authority of thousands of opinions is not worth as much as one tiny spark of reason in an individual man. ~ Galileo Galilei

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. ~ Galileo Galilei

E pur si muove.
(Albeit It does move.)
[What Galileo purportedly muttered after torturers forced him to recant his theory that the earth orbits the sun.] ~ Galileo Galilei

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. ~ Galileo Galilei

I have never met a man so ignorant that I couldn't learn something from him. ~ Galileo Galilei

I see that you have hitherto been one of that herd who, in order to learn how matters such as this take place, and in order to acquire a knowledge of natural effects, do not exhaust themselves in waking and studying, and mortify themselves with experiments and observations, but retire into their studies and glance through an index and a table of contents to see whether Aristotle has said any thing about them; and, being assured of the true sense of his text, consider that nothing else can be known. ~ Galileo Galilei

Showing a greater fondness for their own opinions than for truth, they sought to deny and disprove the new things which, if they had cared to look for themselves, their own senses would have demonstrated to them. ~ Galileo Galilei

The Milky Way is nothing else but a mass of innumerable stars planted together in clusters. ~ Galileo Galilei

Who would dare assert that we know all there is to be known? ~ Galileo Galilei

Nature's great book is written in mathematics. ~ Galileo Galilei

They know that it is human nature to take up causes whereby a man may oppress his neighbor, no matter how unjustly ... Hence they have had no trouble in finding men who would preach the damnability and heresy of the new doctrine from the very pulpit ... ~ Galileo Galilei

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. ~ Mehmet Murat Ildan

The earth, in fair and grateful exchange, pays back to the moon an illumination similar to that which it receives from her throughout nearly all the darkest gloom of the night. ~ Galileo Galilei

The Divine intellect indeed knows infinitely more propositions [than we can ever know]. But with regard to those few which the human intellect does understand, I believe that its knowledge equals the Divine in objective certainty. ~ Galileo Galilei

But why has our physical world revealed such extreme mathematical regularity that astronomy superhero Galileo Galilei proclaimed nature to be "a book written in the language of mathematics," and Nobel Laureate Eugene Wigner stressed the "unreasonable effectiveness of mathematics in the physical sciences" as a mystery demanding an explanation? ~ Max Tegmark

Oh, my dear Kepler, how I wish that we could have one hearty laugh together. Here, at Padua, is the principal professor of philosophy, whom I have repeatedly and urgently requested to look at the moon and planets through my glass, [telescope] which he pertinaciously refuses to do. Why are you not here? what shouts of laughter we should have at this glorious folly! and to hear the professor of philosophy at Pisa laboring before the grand duke with logical arguments, as if with magical incantations, to charm the new planets out of the sky. ~ Galileo Galilei

A men whose every word is nothing but the truth is not a human being but a god! Gods do not die, whereas Aristotle is lying in a grave now. ~ Mehmet Murat Ildan

It is a beautiful and delightful sight to behold the body of the Moon. ~ Galileo Galilei

Innovations, free thinking is blowing like a storm; those that stand in front of it, ignorant scholars like you, false scientists, perverse conservatives, obstinate goats, resisting mules are being crushed under the weight of these innovations. You are nothing but ants standing in front of the giants; nothing but chicks trying to challenge roaring volcanoes! ~ Mehmet Murat Ildan

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 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"? ~ Galileo Galilei

I think that in the discussion of natural problems we ought to begin not with the Scriptures, but with experiments, and demonstrations. ~ Galileo Galilei

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

Holy Scripture could never lie or err ... its decrees are of absolute and inviolable truth. ~ Galileo Galilei

I learned an important lesson: Never take the obvious for granted. Once upon a time, it was so obvious that a four-pound rock would plummet earthward twice as fast as a two-pound rock that no one ever bothered to test it. That is, until Galileo Galilei came along and took ten minutes to perform an elegantly simple experiment that yielded a counterintuitive result and changed the course of history. ~ V.S. Ramachandran

Science proceeds more by what it has learned to ignore than what it takes into account. ~ Galileo Galilei

You cannot teach a person something he does not already know, you can only bring what he does know to his awareness. ~ Galileo Galilei

All truths are easy to understand once they are discovered; the point is to discover them. ~ Galileo Galilei

I truly believe the book of philosophy to be that which stands perpetually open before our eyes, though since it is written in characters different from those of our alphabet it cannot be read by everyone. ~ Galileo Galilei

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 characters in which it is written. 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 is wandering in a dark labyrinth. - Galileo Galilei, The Assayer, 1623 ~ Max Tegmark

To be humane, we must ever be ready to pronounce that wise, ingenious and modest statement 'I do not know'. ~ Galileo Galilei

Among the great men who have philosophized about [the action of the tides], the one who surprised me most is Kepler. He was a person of independent genius, [but he] became interested in the action of the moon on the water, and in other occult phenomena, and similar childishness. ~ Galileo Galilei

But of all other stupendous inventions, what sublimity of mind must have been his who conceived how to communicate his most secret thoughts to any other person, though very far distant either in time or place? And with no greater difficulty than the various arrangement of two dozen little signs upon paper? Let this be the seal of all the admirable inventions of man. ~ Galileo Galilei

The greatest wisdom is to get to know oneself. ~ Galileo Galilei

Nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called into question (much less condemned) upon the testimony of biblical passages. ~ Galileo Galilei

Nothing occurs contrary to nature except the impossible, and that never occurs. ~ Galileo Galilei

I never worry about how many legs my chicken has, about whether it can fly or not, about which cock was her husband; that my hen gives me eggs is enough for me! ~ Mehmet Murat Ildan

My dear Kepler, I wish that we might laugh at the stupidity of the human herd. What do you have to say about the principal philosophers of this academy who are filled with the stubbornness of an asp and do not want to look at either the planets, the moon or the telescope, even though I have freely and deliberately offered them the opportunity a thousand times? Truly, just as the asp stops its ears, so do these philosophers shut their eyes to the light of truth. ~ Galileo Galilei

If the Earth were not subject to any change I would consider the Earth a big but useless body in universe, paralyzed...superfluous and unnatural.Those who so exalt incorruptibility, unchangeability and the like, are, I think, reduced to saying such things both because of inordinate desire they have to live for a long time and because of the terror they have of death...they do not realize that if men were immortal, they would have never come into the world. ~ Galileo Galilei

In the future, there will be opened a gateway and a road to a large and excellent science into which minds more piercing than mine shall penetrate to recesses still deeper. ~ Galileo Galilei

The number of people that can reason well is much smaller than those that can reason badly. If reasoning were like hauling rocks, then several reasoners might be better than one. But reasoning isn't like hauling rocks, it's like, it's like racing, where a single, galloping Barbary steed easily outruns a hundred wagon-pulling horses. ~ Galileo Galilei

Being infinitely amazed, so do I give thanks to God, Who has been pleased to make me the first observer of marvelous things, unrevealed to bygone ages. ~ Galileo Galilei

You can't teach anybody anything, only make them realize the answers are already inside them. ~ Galileo Galilei

Vision, I say, is related to light itself. But of this sensation and the things pertaining to it, I pretend to understand but little; and since even a long time would not suffice to explain that trifle, or even to hint at an explanation, I pass over this in silence. ~ Galileo Galilei

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

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

And yet it moves. ~ Galileo Galilei

Knowing thyself, that is the greatest wisdom. ~ Galileo Galilei

See now the power of truth. ~ Galileo Galilei

To understand the Universe, you must understand the language in which it's written, the language of Mathematics. ~ Galileo Galilei

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

To command their professors of astronomy to refute their own observations is to command them not to see what they do see and not to understand what they do understand. ~ Galileo Galilei

Where the senses fail us, reason must step in. ~ Galileo Galilei

Spots are on the surface of the solar body where they are produced and also dissolved, some in shorter and others in longer periods. They are carried around the Sun; an important occurrence in itself. ~ Galileo Galilei

The hypothesis is pretty; its only fault is that it is neither demonstrated nor demonstrable. Who does not see that this is purely arbitrary fiction that puts nothingness as existing and proposes nothing more than simple noncontradiciton? ~ Galileo Galilei

(T)he increase of known truths stimulates the investigation, establishment, and growth of the arts. ~ Galileo Galilei

The theologians also should not be irritated. For if they find that this opinion is false, then they would be free to condemn it; and if they discover that it is true, they ought to thank those who have opened the way to finding the true sense of the Scriptures and who have prevented them from falling into the grave scandal of condemning a true proposition. ~ Galileo Galilei

Measure what can be measured, and make measurable what cannot be measured. ~ Galileo Galilei

I give infinite thanks to God, who has been pleased to make me the first observer of marvelous things. ~ Galileo Galilei

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

I do not know what to say in a case so surprising, so unlooked for and so novel. ~ Galileo Galilei

In this book, you will encounter various interesting geometries that have been thought to hold the keys to the universe. Galileo Galilei (1564-1642) suggested that "Nature's great book is written in mathematical symbols." Johannes Kepler (1571-1630) modeled the solar system with Platonic solids such as the dodecahedron. In the 1960s, physicist Eugene Wigner (1902-1995) was impressed with the "unreasonable effectiveness of mathematics in the natural sciences." Large Lie groups, like E8-which is discussed in the entry "The Quest for Lie Group E8 (2007)"- may someday help us create a unified theory of physics. in 2007, Swedish American cosmologist Max Tegmark published both scientific and popular articles on the mathematical universe hypothesis, which states that our physical reality is a mathematical structure-in other words, our universe in not just described by mathematics-it is mathematics. ~ Clifford A. Pickover

To excite in us tastes, odors, and sounds I believe that nothing is required in external bodies except shapes, numbers, and slow or rapid movements ... if ears, tongues, and noses were removed, shapes and numbers and motions would remain, but not odors or tastes or sounds. ~ Galileo Galilei

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

I would say here something that was heard from an ecclesiastic of the most eminent degree: The intention of the Holy Spirit is to teach us how one goes to heaven, not how the heavens go. ~ Galileo Galilei

To me, a great ineptitude exists on the part of those who would have it that God made the universe more in proportion to the small capacity of their reason than to His immense, His infinite, power. ~ Galileo Galilei

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. ~ Galileo Galilei

Long experience has taught me this about the status of mankind with regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them, while on the other hand to know and understand a multitude of things renders men cautious in passing judgment upon anything new. ~ Galileo Galilei

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

Philosophy is written in this all-encompassing book that is constantly open to our eyes, that is the universe; but it cannot be understood unless one first learns to understand the language and knows the characters in which it is written. It is written in mathematical language, and its characters are triangles, circles, and other geometrical figures; without these it is humanly impossible to understand a word of it, and one wanders in a dark labyrinth. ~ Galileo Galilei

Wine is sunlight, held together by water. ~ Galileo Galilei

What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth. ~ Bertrand Russell

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. ~ Galileo Galilei

It has always seemed to me extreme presumptuousness on the part of those who want to make human ability the measure of what nature can and knows how to do, since, when one comes down to it, there is not one effect in nature, no matter how small, that even the most speculative minds can fully understand. ~ Galileo Galilei

Nothing can be taught to a man, only it's possibly to help him to discover it inside. ~ Galileo Galilei

I do not think it is necessary to believe that the same God who has given us our senses, reason, and intelligence wished us to abandon their use, giving us by some other means the information that we could gain through them. ~ Galileo Galilei

Man is a 'jar of mistakes', dear Giulia; as we have made a mistake, we are human; this proves it! ~ Mehmet Murat Ildan

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

The number of fixed stars which observers have been able to see without artificial powers of sight up to this day can be counted. It is therefore decidedly a great feat to add to their number, and to set distinctly before the eyes other stars in myriads, which have never been seen before, and which surpass the old, previously known stars in number more than ten times. ~ Galileo Galilei

It's very dangerous to invent something in our times; ostentatious men of the other world, who are hostile to innovations, roam about angrily. To live in peace, one has to stay away from innovations and new ideas. Innovations, like trees, attract the most destructive lightnings to themselves. ~ Mehmet Murat Ildan

It is very pious to say and prudent to affirm that the holy Bible can never speak untruth
whenever its true meaning is understood. But I believe nobody will deny that it is often very abstruse, and may say things which are quite different from wha. ~ Galileo Galilei

The Bible shows the way to go to heaven, not the way the heavens go. ~ Galileo Galilei

Nature is relentless and unchangeable, and it is indifferent as to whether its hidden reasons and actions are understandable to man or not. ~ Galileo Galilei

I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use. ~ Galileo Galilei

We cannot search for the truth and for the way out of suffering without the freedom to think, investigate, and experiment. Secular people cherish freedom, and refrain from investing supreme authority in any text, institution or leader as the ultimate judge of what's true and what's right. Humans should always retain the freedom to doubt, to check again, to hear a second opinion, to try a different path. Secular people admire Galileo Galilei who dared to question whether the earth really sits motionless at the centre of the universe; they admire the masses of common people who stormed the Bastille in 1789 and brought down the despotic regime of Louis XVI; and they admire Rosa Parks who had the courage to sit down on a bus seat reserved for white passengers only. ~ Yuval Noah Harari

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. ~ Ivan Pavlov

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

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. ~ Galileo Galilei

What ever the course of our lives, we should recieve them as the highest gift from the hand of God, in which equally reposed the power to do nothing whatever for us. Indeed, we should accept misfortune not only in thanks, but in infinite gratitude to Providence, which by such means detaches us from an excessive love for Earthly things and elevates our minds to the celestial and divine. ~ Galileo Galilei

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

We are surrounded by the dry thorns of the Inquisition on all four sides; throwing around words burning like fire is the shortest way to one's grave! ~ Mehmet Murat Ildan

I think that tastes, odors, colors, and so on . . .
reside in consciousness. Hence if the living
creature were removed, all these qualities
would be wiped away and annihilated. ~ Galileo Galilei

You may force me to say what you wish; you may revile me for saying what I do. But it moves. ~ Galileo Galilei

The difficulties in the study of the infinite arise because we attempt, with our finite minds, to discuss the infinite, assigning to it those properties which we give to the finite and limited; but this ... is wrong, for we cannot speak of infinite quantities as being the one greater or less than or equal to another. ~ Galileo Galilei