100 Quotes by Galileo Galilei
Galileo Galilei, an Italian astronomer, physicist, and polymath, stands as one of the key figures in the scientific revolution. Through meticulous observations and groundbreaking experiments, he challenged prevailing notions of the cosmos and set the foundation for modern physics. Galileo's advocacy of heliocentrism – the theory that the Earth orbits the Sun – brought him into conflict with the religious and intellectual authorities of his time. Despite facing persecution, he boldly defended his scientific findings, promoting the idea that the natural world could be understood through empirical investigation and mathematical analysis. His work "Dialogue Concerning the Two Chief World Systems" sparked debates that reverberated through history, highlighting the clash between scientific inquiry and established beliefs. Galileo's unwavering commitment to the pursuit of knowledge paved the way for the empirical method and the spirit of rational exploration that underpin modern science.
Galileo Galilei Quotes
For in the sciences the authority of thousands of opinions is not worth as much as one tiny spark of reason in an individual man. (Meaning)
I do not believe that the same God who endowed us with logic, reason, and intellect intended us to avoid their use. (Quote Meaning)
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. (Meaning)
Passion is the genesis of genius. (Quote Meaning)
Doubt is the father of invention. (Meaning)
All truths are easy to understand once they are discovered; the point is to discover them. (Quote Meaning)
I have never met a man so ignorant that I couldn't learn something from him. (Meaning)
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. (Quote Meaning)
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.
The laws of nature are written by the hand of God in the language of mathematics.
Knowing thyself, that is the greatest wisdom.
To understand the Universe, you must understand the language in which it's written, the language of Mathematics. (Meaning)
In the sciences, the authority of thousands of opinions is not worth as much as one tiny spark of reason in an individual man.
To be humane, we must ever be ready to pronounce that wise, ingenious and modest statement 'I do not know'.
You can't teach anybody anything, only make them realize the answers are already inside them.
Mathematics is the language with which God has written the universe.
There are those who reason well, but they are greatly outnumbered by those who reason badly.
Two truths cannot contradict one another.
The Bible shows the way to go to heaven, not the way the heavens go. (Quote Meaning)
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.
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.
Where the senses fail us, reason must step in. (Meaning)
You may force me to say what you wish; you may revile me for saying what I do. But it moves.
Nothing occurs contrary to nature except the impossible, and that never occurs.
You cannot teach a person something he does not already know, you can only bring what he does know to his awareness.
God is known by nature in his works, and by doctrine in his revealed word.
Who would dare assert that we know all there is to be known?
The greatest wisdom is to get to know oneself.
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.
The vain presumption of understanding everything can have no other basis than never having understood anything. For anyone who had ever 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.
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. (Quote Meaning)
Measure what can be measured, and make measurable what cannot be measured. (Meaning)
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"?
Measure what is measurable, and make measurable what is not so.
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.
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.
With regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them.
Mathematics is the key and door to the sciences.
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. (Quote Meaning)
The book of nature is written in the language of mathematics.
Wine is sunlight, held together by water. (Meaning)
Holy Scripture could never lie or err...its decrees are of absolute and inviolable truth.
I think that in the discussion of natural problems we ought to begin not with the Scriptures, but with experiments and demonstrations. (Quote Meaning)
It is surely harmful to souls to make it a heresy to believe what is proved.
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.
And believe me, if I were again beginning my studies, I should follow the advice of Plato and start with the mathematical sciences, which proceed very cautiously and admit nothing as established until it has been rigorously demonstrated.
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?
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.
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.
The Milky Way is nothing else but a mass of innumerable stars planted together in clusters.
It is a beautiful and delightful sight to behold the body of the Moon. (Meaning)
Nature is relentless and unchangeable. (Quote Meaning)
Science proceeds more by what it has learned to ignore than what it takes into account.
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.
Scripture is a book about going to Heaven. It's not a book about how the heavens go.
In regard to the philosophers, if they be true philosophers, i.e., lovers of truth, they should not be irritated that the earth moves. Rather, if they realize that they have held a false belief, they should thank those have shown them the truth; and if their opinion stands firm that the earth doesn't move, they will have reason to boast than be angered.
See now the power of truth.
But let us remember that we are dealing with infinities and indivisibles both of which transcend our finite understanding, the former on account of their magnitude, the latter because of their smallness.
The laws of Nature are written in the language of mathematics...the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word.
By denying scientific principles, one may maintain any paradox.
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.
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.
Philosophy itself cannot but benefit from our disputes, for if our conceptions prove true, new achievements will be made; if false, their refutation will further confirm the original doctrines.
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.
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.
Nature is inexorable and immutable; she never transgresses the laws imposed upon her, nor cares a whit whether her abstruse reasons and methods of operations are understandable to men.
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.
It vexes me when they would constrain science by the authority of the Scriptures, and yet do not consider themselves bound to answer reason and experiment.
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.
Nature...does not act by means of many things when it can do so by means of a few.
Nature is written in mathematical language.
I am inclined to think that the authority of Holy Scripture is intended to convince men of those truths which are necessary for their salvation, which, being far above man's understanding, can not be made credible by any learning, or any other means than revelation by the Holy Spirit.
Philosophy is written in that great book which ever lies before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written.
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.
The doctrine that the earth is neither the center of the universe nor immovable, but moves even with a daily rotation, is absurd, and both philosophically and theologically false, and at the least an error of faith.
Nature's great book is written in mathematics.
I believe that the intention of Holy Writ was to persuade men of the truths necessary to salvation; such as neither science nor other means could render credible, but only the voice of the Holy Spirit.
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.
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.
They who depend upon manifest observations will philosophize better than those who persist in opinions repugnant to the senses.
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.
Facts which at first seem improbable will, even on scant explanation, drop the cloak which has hidden them and stand forth in naked and simple beauty. (Meaning)
I do not know what to say in a case so surprising, so unlooked for and so novel.
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.
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.
Nothing can be taught to a man, only it's possibly to help him to discover it inside.
Some, merely to contradict what I had said, did not scruple to cast doubt upon things they had seen with their own eyes again and again.
The surface of the Moon is not smooth, uniform, and precisely spherical as a great number of philosophers believe it to be, but is uneven, rough, and full of cavities and prominences, being not unlike the face of the Earth, relieved by chains of mountains and deep valleys.
I abjure with a sincere heart and unfeigned faith, I curse and detest the said errors and heresies, and generally all and every error and sect contrary to the Holy Catholic Church.
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.
We must say that there are as many squares as there are numbers.
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.
In time you may discover everything that can be discovered, and still your progress will only be progress away from humanity. The distance between you and them can one day become so great that your joyous cry over some new gain could be answered by an universal shriek of horror.
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.
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!
Holy Writ was intended to teach men how to go to Heaven not how the heavens go.
The Universe is a grand book which cannot be read until one first learns to comprehend the language and become familiar with the characters in which it is composed. It is written in the language of mathematics.
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.
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.
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.
[Copernicus] 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.
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.
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.
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.
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.
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.
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!
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.
The number of the 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.
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.
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.
One can understand nature only when one has learned the language and the signs in which it speaks to us; but this language is mathematics and these signs are mathematical figures.
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 than our own eyes?
It was granted to me alone to discover all the new phenomena in the sky and nothing to anybody else. This is the truth which neither envy nor malice can suppress.
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 Quotes
Chief Editor
Tal Gur is an author, founder, and impact-driven entrepreneur at heart. After trading his daily grind for a life of his own daring design, he spent a decade pursuing 100 major life goals around the globe. His journey and most recent book, The Art of Fully Living, has led him to found Elevate Society.
