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Who really said it

Mathematics is the language with which God has written the universe

Galileo’s idea — but not his words Galileo Galilei 1564–1642 · Italian astronomer, physicist and mathematician
The thought is documented. The sentence is a paraphrase. Free to reuse

There is a real passage behind this, in Il Saggiatore (1623), and Galileo really did say the universe is written in the language of mathematics. But he wrote it the other way round — philosophy is the book, mathematics is the language it is set in — and the Italian original ↗ does not mention God at all.

Last verified 23 Aug 2026 · how we verify · spot an error?

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Disputed wording — copy with the correction

“Mathematics is the language with which God has written the universe” A paraphrase, not Galileo's sentence. What he wrote, in Il Saggiatore (1623), is: "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. This book is written in the mathematical language..." (trans. E. A. Burtt, The Metaphysical Foundations of Modern Physical Science, London: Kegan Paul, Trench, Trubner, 1925). God does not appear in the Italian.

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In context

Evoking the world of Galileo Galilei — Italian astronomer, physicist, engineer and polymath. Theme: "Mathematics is the language with which God has written the universe". 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

What Galileo actually wrote

Work
Il Saggiatore (The Assayer)
Published
Rome, 1623
Italian original
“La filosofia è scritta in questo grandissimo libro che continuamente ci sta aperto innanzi a gli occhi (io dico l’universo)… Egli è scritto in lingua matematica”
Translation shown
E. A. Burtt, The Metaphysical Foundations of Modern Physical Science (London: Kegan Paul, Trench, Trübner, 1925)

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. This book is written in the mathematical language, and the symbols are triangles, circles, and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth.

Burtt’s 1925 translation. Note what is missing: no God, and the book that is “written” is the universe, with mathematics as the alphabet — not mathematics as the writing and God as the writer.

The Italian original in the Edizione Nazionale, vol. 6

How we verified this

  • Wikiquote’s sourced section for Il Saggiatore ↗ carries the passage, the Italian, and three separate English translations. None of them — and no other entry on that page — contains the words “God has written the universe.”
  • We read the Italian ourselves. The page of Favaro’s Edizione Nazionale, volume 6 ↗ has “La filosofia è scritta in questo grandissimo libro… Egli è scritto in lingua matematica, e i caratteri son triangoli, cerchi, ed altre figure geometriche.” There is no Dio in the sentence.
  • We read a translation rather than trusting one. E. A. Burtt’s The Metaphysical Foundations of Modern Physical Science ↗ renders it as quoted above; its title page reads London: Kegan Paul, Trench, Trübner & Co., 1925. Wikiquote cites this translation at p. 64.
  • What we could not establish: where the “God has written” wording came from, or when it first appeared in print. We found no source that documents its origin, so we do not name one.
Public domain

The status covers the passage quoted on this page — Galileo’s 1623 Italian and the English translation shown — not the paraphrase in the headline. Il Saggiatore was published in Rome in 1623, and the wording we print is E. A. Burtt’s ↗, from a book whose title page is dated 1925 — comfortably before the 1931 threshold for US public domain. The popular sentence has no identified source, so no rights claim is made for it.

This reflects the original work, which is public domain. If your exact English wording comes from a specific modern translation, that translation may itself still be under copyright — check the edition you quote.

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

How the sentence drifted

Nobody is falsely credited here. The author is right, the book is right, and the words are wrong in two specific ways.

“Mathematics is the language…” Reworded — subject and language swapped

Galileo’s subject is philosophy, written in the book of the universe; mathematics is the language that book is set in. The Italian ↗ opens “La filosofia è scritta in questo grandissimo libro.”

“…with which God has written the universe” Not in the source

No word for God appears in the sentence in the Edizione Nazionale text ↗, and none appears in any of the three translations Wikiquote prints ↗. The theology is an addition.

Unknown We could not trace it

We found no source documenting when or where the popular wording first appeared, and we are not going to guess. It is reported everywhere and sourced nowhere.

The idea is Galileo’s and the book is real. What he wrote ↗ is that the universe is the book, and mathematics is the language it is written in.

Context

Why it mattered

Il Saggiatore was published in 1623 as a quarrel about comets, aimed at a Jesuit rival. The passage that outlived the quarrel is a claim about method: that nature is legible, and that the way to read it is not authority or rhetoric but geometry.

That is why the sentence gets quoted at all. It is one of the earliest clean statements of the idea that physics should be mathematical — and the reason a paraphrase of it is welded to Galileo’s name on a million posters.

He did not say God wrote the universe. He said we have to learn to read it.

Read the full story

The drift is worth noticing because it changes the argument. Galileo’s version is epistemological: the book is open, and the problem is our illiteracy. The popular version is theological: the universe is a divine text. The second is a comfortable sentiment; the first was a fighting position, and it is the one that got him into trouble.

Three English translations of the passage are in wide circulation — Burtt’s of 1925, Drake’s, and Richard Popkin’s of 1966. We quote Burtt’s because it is the one whose copyright has clearly expired, and because we could read its title page ourselves.

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Filed under

More provenance-checked quotes on the same theme, each with its reuse status.

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Dig deeper

Trusted places to keep pulling the thread — primary archives, fact-checks, and scholarship. We show how we used each one before you leave.

Wikiquote: Galileo Galileien.wikiquote.org

The sourced Il Saggiatore entry, with the Italian and three English translations. None uses the word God.
Le opere di Galileo Galilei, vol. 6it.wikisource.org

The Italian original of the passage in Favaro’s national edition.
Burtt, The Metaphysical Foundations of Modern Physical Science (1925)archive.org

The public-domain English translation quoted on this page; full scan, title page dated 1925.
Wikipedia: The Assayeren.wikipedia.org

Background on Il Saggiatore, the 1623 polemic on comets in which the passage appears.
Wikipedia: Galileo Galileien.wikipedia.org

Life and work of the author, including the Copernican dispute that followed Il Saggiatore.

The author

About Galileo Galilei

Galileo Galilei

1564–1642 · Italian astronomer, physicist, engineer and polymath

Galileo Galilei was born in Pisa in 1564 and has been called the father of observational astronomy, of classical physics and of the scientific method. Il Saggiatore (1623), where this passage appears, is nominally an argument about comets and actually a manifesto: nature is to be read, and the reading is done in mathematics. He argued the Copernican case in the Dialogue of 1632, was condemned for it in 1633, and spent his last years under house arrest.

For writers & researchers

Cite this

The primary source (Chicago)

Galileo Galilei, Il Saggiatore (Rome, 1623), in Le opere di Galileo Galilei, Edizione Nazionale, ed. Antonio Favaro, vol. 6 (Florence: Tipografia di G. Barbèra, 1896); English wording from Edwin Arthur Burtt, The Metaphysical Foundations of Modern Physical Science (London: Kegan Paul, Trench, Trübner & Co., 1925). The popular sentence “Mathematics is the language with which God has written the universe” is a paraphrase with no located source.

This verification page

Quotle.info. “Who really said ‘Mathematics is the language with which God has written the universe’?” Last verified 23 Aug 2026. https://quotle.info/who-said/mathematics-is-the-language-with-which-god-has-written-the/

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