The thought is genuinely Galileo’s: writing to the Augsburg scholar Marc Welser on 1 December 1612, he argued that “l’autorità dell’opinione di mille nelle scienze non val per una scintilla di ragione di un solo” — the authority of a thousand opinions in the sciences is not worth one spark of reason in a single man. But this exact English sentence is not something Galileo wrote. It is the W. H. Smyth / Baden Powell / Robert Grant translation of François Arago’s French memoir of Laplace — a piece Arago drew from his report for a Chamber of Deputies committee nominated in 1842 — printed at p. 365 of the Boston 1859 edition ↗. Arago paraphrases Galileo there and names no source.
“In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual” attributed to Galileo Galilei. The English wording is François Arago's, in Biographies of Distinguished Scientific Men, First Series (Boston: Ticknor and Fields, 1859), p. 365; Galileo's own sentence appears in his third letter on sunspots to Marc Welser, 1 December 1612.
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Evoking the world of Galileo Galilei — Italian astronomer, physicist and mathematician. Theme: "In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual". Atmospheric and restrained, cinematic directional light, a muted period-appropriate palette, fine grain and texture. Compose with generous empty space for the quote and a small credit line. No lettering in the image itself.
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Provenance
Where the sentence actually comes from
Written
Third Letter on Sunspots, to Marc Welser
Dated
Villa delle Selve, 1 December 1612
Published in
Istoria e dimostrazioni intorno alle macchie solari (Rome: Accademia dei Lincei, 1613)
Translation
The popular English wording is François Arago’s, Englished by W. H. Smyth, Baden Powell and Robert Grant (Boston, 1859), p. 365
A philosopher, whose name is associated with immortal discoveries, said to his audience who had allowed themselves to be influenced by ancient and consecrated authorities, “Bear in mind, Gentlemen, that in questions of science the authority of a thousand is not worth the humble reasoning of a single individual.” Two centuries have passed over these words of Galileo without depreciating their value, or obliterating their truthful character.
Arago on Laplace, 1859, p. 365
That is the passage the modern quotation comes out of — Arago’s, not Galileo’s, and offered without a citation. Galileo’s own sentence, in the third sunspot letter, runs: “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.”
Galileo wrote it to the Augsburg scholar Marc Welser from the Villa delle Selve on 1 December 1612. The Italian of the third sunspot letter ↗ reads “l’autorità dell’opinione di mille nelle scienze non val per una scintilla di ragione di un solo.”
The same Baden Powell translation was reprinted in the Smithsonian Annual Report for 1874 ↗, under the heading “Laplace — Eulogy by Arago before the French Academy,” which is how the 1874 date entered later citations.
Wikiquote ↗ lists the popular sentence as a variant translation of that sunspot-letter passage, citing Arago 1859 at p. 365 — it does not place it among the misattributed or disputed quotations.
✓Public domain
Galileo’s Italian was published in Rome in 1613, and the English wording shown here comes from the 1859 Boston edition of Arago’s biographies — both are long in the public domain in the United States. The standard modern scholarly translation of the sunspot letters, Stillman Drake’s Discoveries and Opinions of Galileo (1957), is a separate work still in copyright and is not reproduced here.
Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.
Fact-check
What actually gets misattributed here
Nobody has to take this line away from Galileo — the argument really is his. What travels falsely is the sentence itself, and the scene it is usually wrapped in.
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The wordingFrançois Arago, not Galileo’s pen paraphrase
Galileo’s Italian speaks of “una scintilla di ragione” — a spark of reason. “The humble reasoning of a single individual” is Arago’s phrasing, reaching English through W. H. Smyth, Baden Powell and Robert Grant in the 1859 Boston edition ↗. It is a fair rendering of the sense, but it is not a translation anyone made from Galileo’s text.
✕
The settingAn audience that was never there invented scene
Arago introduces the line as something a philosopher “said to his audience… Bear in mind, Gentlemen,” which is how it is still quoted — as a lecture-hall retort. The only documented text is a private letter to Marc Welser ↗, written from the Villa delle Selve. Arago cites no source for the spoken version.
✕
The citation“Arago, Eulogy of Galileo (1874)” wrong eulogy
MacTutor ↗ sources the line that way, and the label gets copied. The 1874 volume that carries Arago in English is the Smithsonian Annual Report ↗, and the section it sits in is headed “Laplace — Eulogy by Arago before the French Academy.” The sentence is a passing aside inside a tribute to Laplace.
✓Galileo made this argument, in writing, to Marc Welser on 1 December 1612. The sentence people quote was written by François Arago ↗, about Laplace, more than two centuries later.
Context
Why he was in a mood to say it
In 1612 Galileo was in a running argument about sunspots with a writer hiding behind the pen name “Apelles” — the Jesuit astronomer Christoph Scheiner. Both were watching the same dark blotches crawl across the sun’s face; they disagreed about what the blotches were and, more importantly, about how you settle such a question. Apelles leaned on what was, by his account, the common opinion of all philosophers and mathematicians.
That is the sentence Galileo was answering when he wrote the line. His reply is not a general hymn to individualism — it is a specific procedural point about how evidence beats consensus, made sharper by the observation that follows it: the old writers would have judged differently if they had seen what the telescope now showed.
Present observations strip the decrees of past writers of their authority — writers who, had they seen these things themselves, would have decided otherwise.
Read the full story
The three sunspot letters were addressed to Marc Welser, an Augsburg banker and scholar who was relaying Scheiner’s work to Galileo. They were collected and published in Rome by the Accademia dei Lincei in 1613 as Istoria e dimostrazioni intorno alle macchie solari.
Arago reached for the line nearly two and a half centuries later for a very different purpose: he was writing about Laplace and wanted a warrant for judging a great mathematician’s work on its merits rather than by counting his admirers.
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More provenance-checked quotes on the same theme, each with its reuse status.
1564–1642 · Italian astronomer, physicist and mathematician
Galileo Galilei turned an improved spyglass on the night sky in 1609 and spent the rest of his life arguing about what he saw there. The sunspot letters of 1612 caught him mid-fight with a rival observer writing under the pseudonym “Apelles” — later identified as the Jesuit Christoph Scheiner — and the exchange is where he set out most sharply his conviction that observation beats inherited authority. Two decades later that same conviction put him in front of the Roman Inquisition.
For writers & researchers
Cite this
Chicago
Galileo Galilei, third letter on sunspots to Marc Welser, Villa delle Selve, 1 December 1612, in Istoria e dimostrazioni intorno alle macchie solari (Rome: Accademia dei Lincei, 1613). The familiar English wording is from François Arago, Biographies of Distinguished Scientific Men, First Series, trans. W. H. Smyth, Baden Powell, and Robert Grant (Boston: Ticknor and Fields, 1859), 365.
This verification page
Quotle.info. “Who really said ‘In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual’?” Last verified 24 Aug 2026. https://quotle.info/who-said/in-questions-of-science-the-authority-of-a-thousand-is-not/