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Home > Dictionary of Science Quotations > Scientist Names Index G > Galileo Galilei Quotes > Observation

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Galileo Galilei
(15 Feb 1564 - 8 Jan 1642)

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

Galileo Galilei Quotes on Observation (6 quotes)

>> Click for 49 Science Quotes by Galileo Galilei

>> Click for Galileo Galilei Quotes on | Heliocentric Model | Moon | Religion | Telescope |

Alas, your dear friend and servant is totally blind. Henceforth this heaven, this universe, which by wonderful observations I had enlarged by a hundred and a thousand times beyond the conception of former ages, is shrunk for me into the narrow space which I myself fill in it. So it pleases God; it shall therefore please me also.
— Galileo Galilei
In Letter, as quoted in Sir Oliver Lodge, Pioneers of Science (1905), 133.
Science quotes on:  |  Age (100)  |  Blind (23)  |  Conception (49)  |  Enlarge (12)  |  Former (8)  |  Heaven (102)  |  Hundred (24)  |  Narrow (25)  |  Observation (378)  |  Shrink (5)  |  Space (116)  |  Thousand (75)  |  Universe (421)  |  Wonderful (23)

For the holy Bible and the phenomena of nature proceed alike from the divine Word, the former as the dictate of the Holy Ghost and the latter as the observant executrix of God's commands. It is necessary for the Bible, in order to be accommodated to the understanding of every man, to speak many things which appear to differ from the absolute truth so far as the bare meaning of the words is concerned. But Nature, on the other hand, is inexorable and immutable; she never transgresses the laws imposed upon her, or cares a whit whether her abstruse reasons and methods of operation are understandable to men. For that reason it appears that nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words.
— Galileo Galilei
Letter to Madame Christina of Lorraine, Grand Duchess of Tuscany: Concerning the Use of Biblical Quotations in Matters of Science (1615), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 182-3.
Science quotes on:  |  Experiment (487)  |  God (315)  |  Law (363)  |  Nature (820)  |  Observation (378)  |  Truth (636)

I cannot but be astonished that Sarsi should persist in trying to prove by means of witnesses something that I may see for myself at any time by means of experiment. Witnesses are examined in doutbful matters which are past and transient, not in those which are actual and present. A judge must seek by means of witnesses to determine whether Peter injured John last night, but not whether John was injured, since the judge can see that for himself.
— Galileo Galilei
'The Assayer' (1623), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 271.
Science quotes on:  |  Experiment (487)  |  Observation (378)  |  Truth (636)

I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations.
Referring to his pioneering telescope observations.
— Galileo Galilei
The Starry Messenger (Mar 1610). Quoted in Edmund Blair Bolles, Galileo's Commandment (1999), 104.
Science quotes on:  |  Jupiter (16)  |  Mercury (39)  |  Observation (378)  |  Telescope (67)  |  Venus (11)

Nor need you doubt that Pythagoras, a long time before he found the demonstration for the Hecatomb, had been certain that the square of the side subtending the right angle in a rectangular triangle was equal to the square of the other two sides; the certainty of the conclusion helped not a little in the search for a demonstration. But whatever was the method of Aristotle, and whether his arguing a priori preceded sense a posteriori, or the contrary, it is sufficient that the same Aristotle (as has often been said) put sensible experiences before all discourses. As to the arguments a priori, their force has already been examined.
— Galileo Galilei
Dialogue on the Great World Systems (1632). Revised and Annotated by Giorgio De Santillana (1953), 60.
Science quotes on:  |  Aristotle (130)  |  Observation (378)  |  Pythagoras (25)

…I distinguish two parts of it, which I call respectively the brighter and the darker. The brighter seems to suround and pervade the whole hemisphere; but the darker part, like a sort of cloud, discolours the Moon's surface and makes it appear covered with spots. Now these spots, as they are somewhat dark and of considerable size, are plain to everyone and every age has seen them, wherefore I will call them great or ancient spots, to distinguish them from other spots, smaller in size, but so thickly scattered that they sprinkle the whole surface of the Moon, but especially the brighter portion of it. These spots have never been observed by anyone before me; and from my observations of them, often repeated, I have been led to the opinion which I have expressed, namely, that I feel sure that the surface of the Moon is not perfectly smooth, free from inequalities and exactly spherical... but that, on the contrary, it is full of inequalities, uneven, full of hollows and protuberances, just like the surface of the Earth itself, which is varied everywhere by lofty mountains and deep valleys.
Describing his pioneering telecope observations of the Moon made from Jan 1610.
— Galileo Galilei
The Starry Messenger (Mar 1610). Quoted in Patrick Moore, Patrick Moore on the Moon (2006), 56.
Science quotes on:  |  Crater (6)  |  Moon (114)

See also:
  • 15 Feb - short biography, births, deaths and events on date of Galilei's birth.
  • Galileo Galilei - Quotations - Abjuration
  • Galileo Gailei - biography from Famous Men of Science (1889).
  • Galileo - “And Yet It Moves” illustrated quote - Medium 500px
  • Galileo - “And Yet It Moves” illustrated quote - Large 800px
  • Galileo: A Life, by James Reston. - book suggestion.
  • Booklist for Galileo Galilei.

Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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