Galileo di Vincenzo Bonaiuti de’ Galilei, commonly referred to as Galileo Galilei or simply Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a polymath. He was born in the city of Pisa, then part of the Duchy of Florence.

Galileo Galilei Quotes

1. “Mathematics is the language with which God has written the universe.”
— Galileo Galilei

2. “The book of nature is written in the language of mathematics.”
— Galileo Galilei

3. “Mathematics is the key and door to the sciences.”
— Galileo Galilei

4. “Passion is the genesis of genius.”
— Galileo Galilei

5. “Eppur si muove.”
— Galileo Galilei

6. “To understand the Universe, you must understand the language in which it’s written, the language of Mathematics.”
— Galileo Galilei

7. “We cannot teach people anything; we can only help them discover it within themselves.”
— Galileo Galilei

8. “I’ve loved the stars too fondly to be fearful of the night.”
— Galileo Galilei

9. “I have never met a man so ignorant that I couldn’t learn something from him.”
— Galileo Galilei

10. “Measure what is measurable, and make measurable what is not so.”
— Galileo Galilei

11. “Nature’s great book is written in mathematics.”
— Galileo Galilei

12. “I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forego their use.”
— Galileo Galilei

13. “If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.”
— Galileo Galilei

14. “All truths are easy to understand once they are discovered; the point is to discover them.”
— Galileo Galilei

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

16. “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.”
— Galileo Galilei

17. “The Bible shows the way to go to heaven, not the way the heavens go.”
— Galileo Galilei

18. “Where the senses fail us, reason must step in.”
— Galileo Galilei

19. “Two truths cannot contradict one another.”
— Galileo Galilei

20. “Knowing thyself, that is the greatest wisdom.”
— Galileo Galilei

21. “God is known by nature in his works, and by doctrine in his revealed word.”
— Galileo Galilei

22. “The greatest wisdom is to get to know oneself.”
— Galileo Galilei

23. “You can’t teach anybody anything, only make them realize the answers are already inside them.”
— Galileo Galilei

24. “Wine is sunlight, held together by water.”
— Galileo Galilei

25. “Nonetheless, it moves.”
— Galileo Galilei

26. “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

27. “In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.”
— Galileo Galilei

28. “By denying scientific principles, one may maintain any paradox.”
— Galileo Galilei

29. “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

30. “The Milky Way is nothing else but a mass of innumerable stars planted together in clusters.”
— Galileo Galilei

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

32. “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.”
— Galileo Galilei

33. “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.”
— Galileo Galilei

34. “Nothing occurs contrary to nature except the impossible, and that never occurs.”
— Galileo Galilei

35. “See now the power of truth.”
— Galileo Galilei

36. “It is a beautiful and delightful sight to behold the body of the Moon.”
— Galileo Galilei

37. “There are those who reason well, but they are greatly outnumbered by those who reason badly.”
— Galileo Galilei

38. “Man kann einen Menschen nichts lehren. Man kann ihm nur helfen, es in sich selbst zu finden!”
— Galileo Galilei

39. “Science proceeds more by what it has learned to ignore than what it takes into account.”
— Galileo Galilei

40. “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

41. “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

42. “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

43. “Who would dare assert that we know all there is to be known?”
— Galileo Galilei

44. “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

45. “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

46. “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

47. “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

48. “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

49. “Scripture is a book about going to Heaven. It’s not a book about how the heavens go.”
— Galileo Galilei

50. “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.”
— Galileo Galilei

51. “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

52. “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

53. “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

54. “Infinities and indivisibles transcend our finite understanding, the former on account of their magnitude, the latter because of their smallness; Imagine what they are when combined.”
— Galileo Galilei

55. “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

56. “It is surely harmful to souls to make it a heresy to believe what is proved.”
— Galileo Galilei

57. “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

58. “We must say that there are as many squares as there are numbers.”
— Galileo Galilei

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

60. “They who depend upon manifest observations will philosophize better than those who persist in opinions repugnant to the senses.”
— Galileo Galilei

61. “With regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them.”
— Galileo Galilei

62. “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 methematical figures.”
— Galileo Galilei

63. “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

64. “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

65. “Nothing can be taught to a man, only it’s possibly to help him to discover it inside.”
— Galileo Galilei

66. “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.”
— Galileo Galilei

67. “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

68. “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.”
— Galileo Galilei

69. “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.”
— Galileo Galilei

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

71. “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

72. “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.”
— Galileo Galilei

73. “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 supress.”
— Galileo Galilei

74. “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

75. “They seemed to forget that the increase of known truths stimulates the investigation, establishment and growth of the arts; not their dimination or destruction.”
— Galileo Galilei

76. “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!”
— Galileo Galilei

77. “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

78. “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

79. “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

80. “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

81. “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

82. “To our natural and human reason, I say that these terms ‘large,’ ‘small,’ ‘immense,’ ‘minute,’ etc. are not absolute but relative; the same thing in comparison with various others may be called at one time ‘immense’ and at another ’imperceptible.”
— Galileo Galilei

83. “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

84. “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.”
— Galileo Galilei

85. “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.”
— Galileo Galilei

86. “Holy Writ was intended to teach men how to go to Heaven not how the heavens go.”
— Galileo Galilei

87. “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.”
— Galileo Galilei

88. “There is not a single effect in Nature, not even the least that exists, such that the most ingenious theorists can ever 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 attained, would recognise that of the infinity of other truths he understands nothing.”
— Galileo Galilei

89. “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

90. “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.”
— Galileo Galilei

91. “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

92. “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

93. “Who would set a limit to the mind? Who would dare assert that we know all there is to be known?”
— Galileo Galilei

94. “The fear of infinity is a form of myopia that destroys the possibility of seeing the actual infinite, even though it in its highest form has created and sustains us.”
— Galileo Galilei

95. “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

96. “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

97. “I entertain no doubts as to the truth of the transfinites, which I have recognized with God’s help.”
— Galileo Galilei

98. “All inconveniences will be removed as you propound them. Up to this point, only the first and most general reasons have been mentioned which render it not entirely improbable that the daily rotation belongs to the earth rather than to the rest of the universe.”
— Galileo Galilei