Anagram and Gergo (Jargon): Galileo's Secret Communication

It is well-known that Galileo Galilei used anagrams to claim a discovery without disclosing the content, the practice also used by other scientists such as Isaac Newton, Christiaan Huygens, and Robert Hooke. Less known is a word substitution code called gergo (jargon) used in later years.

Galileo's Anagrams (1610)

Galileo composed two anagrams in 1610 about discoveries with his telescope.

Sidereal Messenger

After the telescope was invented in Holland in 1608, Galileo built his own in 1609, and published Sidereal Messenger in March 1610, in which he disclosed his discovery about imperfectness of the Moon and Jupiter's satellites.

(By the way, when drafting Sidereal Messenger, Galileo experimented with creating a meaningless Latin phrase by inserting consonants between vowels of a given sequence (presumably extracted from a true message) (Marcus and Findlen, p.961-962).)

Galileo sent a copy of the book to the Tuscan ambassador at Prague, where the imperial court resided at the time. The copy was accompanied by a request for comments from Johannes Kepler, imperial mathematician to Emperor Rudolf II. Kepler quickly replied in a letter of 19 April, which he had printed in May under the title "Conversation with the Sidereal Messenger" (Rosen p.xiv). Kepler endorsed Galileo's observations and offered his own speculations (Wikipedia).

Ring of Saturn

Galileo sent his first anagram to Kepler (via the Tuscan ambassador) in August 1610 (Marcus and Findlen, p.963) .

Anagram: smaismrmilmepoetaleumibunenugttauiras
Solultion: altissimum planetam tergeminum observavi ("I have observed that the highest planet, triple bodied.")

The "highest planet" refers to Saturn in the Aristotelian celestial model. Here, Galileo refers to his discovery of the ring of Saturn. (With the limited power of his telescope, the ring appeared to be protrusions on either side of the planet.)

The astronomical enigma attracted the interests not only of Kepler, but also many at the imperial court, including the emperor himself. Galileo appears to have revealed the solution later in the year (ibid. p.967, 963, 965), though he had privately disclosed his observation to the internal court circles in Florence as early as July (ibid. p.967) (not as the solution of the anagram, this being before its creation).

In the meantime, Kepler had come up with his solution (p.966-967):

Salve umbistineum geminatum Martia proles ("Hail, satellites, children of Mars")

It is as if Kepler coincidentally predicted the two satellites of Mars, which in fact would not be discovered until the nineteenth century. In his attempts to solve the enigma, Kepler must have made various assumptions about the content. The possibility of "two satellites of Mars" had been mentioned in Conversation with the Sidereal Messenger (Rosen p.14, Marcus and Findlen p.967).

Phases of Venus

Galileo sent his second anagram in December 1610 (Marcus and Findlen p.969-970).

Anagram: Haec immatura a me iam frustra leguntur o.y.
Solution: Cynthiae figuras aemulatur mater amorum ("The mother of love imitates the shape of Cynthia")

The recovered statement means Venus (the mother of love) assumes all the phases of the Moon (Cynthia).

It had a revolutionary implication in astronomy at the time. While his earlier discoveries about the Moon and Jupiter already embarrassed the believers of Aristotelian cosmology, the observation of phases of Venus was decisive in converting Galileo to the Copernican view (ibid. p.970). Today, it is well-known that Venus waxes and wanes as the Moon. When Venus is to either side of the sun, it is crescent; when Venus is farther from the sun, it is like full moon. But this holds only in heliocentricism. In Ptolemy's geocentricism, Venus is always closer to the earth than the sun, which means Venus should never become "full moon." Galileo realized that this traditional view of the heaven could not explain what he saw with his telescope.

Again, Kepler could not solve the puzzle. On 9 January 1611, he wrote to Galileo, confessing that the best he came up with was:

Nam Iovem gyrari macula hem rufa testatur. ("Ahah! A witness that Jupiter is turned by a red spot.")

It was followed by "other imperfect solutions", including:

Macula rufa in Iove est gyratur mathem etc. ("There is a red spot on Jupiter that revolves mathematically, etc.") (The number of letters does not match for a, c, e, i, l, m, r, and t, hence "imperfece".)

(Again, it is as if Kepler coincidentally predicted the Great Red Spot on Jupiter.)

This time, Galileo sent the solution dated 1 January 1611 to the imperial court as a New Year's gift, which crossed Kepler's concession of defeat. (ibid. p.970)

Kepler published Galileo's solution in Dioptrics (1611) (ibid. p.971, Fig. 4).

Gergo: Word Substitution Code (1633)

In 1616, possibly stimulated by the new impetus of heliocentricism sparked by Galileo's discoveries, the Church suspended Copernicus's De Revolutionibus (1543) pending correction, and ordered Galileo to abandon heliocentricism. Although he stayed away from the controversy for some time, Galileo published Dialogue Concerning the Two Chief World Systems in 1632. Although the narrative took the form a dialogue between defenders of the two opposing views, it was interpreted as advocating heliocentricism. Galileo was summoned to Rome, and was condemned on 22 June 1633. (Wikipedia)

After the sentence, Galileo used secret code called gergo in his correspondence. I learned this from Marcus and Findlen (2019), p.974 ff. (I thank DPJA Scheers for drawing my attention to this paper.) Unlike anagrams used in 1610, Galileo now had reason to keep his correspondence confidential.

Gergo is mentioned in a letter of Geri Bocchineri, brother-in-law of Galileo's son and a mid-level Tuscan court official (private secretary of the Grand Duke's secretary of state) (Marcus and Findlen p.975, 981), to Galileo dated 9 July 1633, mentioning Galileo's letters of 26 June and 3 July. Apparently, Galileo complained that he could not decipher a previous letter Bocchineri had written "in gergo." Bocchineri explained that it could not be read without the key separately sent. (ibid. p.975)

Although letters from Galileo seem to be lost, Galileo seems have expressed concern about the lost key falling into wrong hands, for Bocchineri reassured him that he used trustworthy people for conveyance and told him "to set aside any doubts about what happened to the key" (4 August) (ibid. p.979-980).

Gergo, literally "jargon," is defined in an Italian dictionary (1691) as: "To speak obscurely, and through metaphor ... or through allusion ... or invented words, like gonzo for countryman, morsia for mouth, stefano for belly .... And he would say that I taught you how to speak in gergo, or rather in cipher [in gergo, ovvero in cifra]." (ibid. p.976) That is, this is word substitution, also called merchant's code, of which hundreds of keys are found in the Italian archives (ibid. p.978). Gergo is also mentioned in a treatise of Matteo Argenti, a generation before Galileo (Marcus and Findlen p.986, Meister p.165, l.4).

Bocchineri's following words may refer to the nature of gergo, but to me, it seems to be simply saying that the jargon list should be ordered alphabetically.

But now it occurs to me that I would have told you to put it in alphabetical order, as I would have done here, comparing it to the other names that are not alphabetized in this key to facilitate deciphering what was written here. I had not hoped that you would come so soon to Siena. (Marcus and Findlen p.980)

(By the way, the last sentence explains the reason Galileo did not receive the key. He left Rome earlier than expected for Siena, where he had to spend six months as a prisoner, albeit being treated as an esteemed guest at the residence of Archbishop Ascanio Piccolomini (ibid. p.975). )

Marcus and Findlen (2019) considers the secret discussed in gergo at this period was the plan to remove papers from Galileo's house in Arcetri, for fear some incriminating evidence might be found by the ecclesiastical authority. The house-cleaning was conducted with Galileo's daughter's cooperation. (ibid. p.980-981)

(Earlier on, when "the Inquisition's rumblings against him had begun to be heard", Galileo had a bricklayer make a hiding place in his villa, where he hid his manuscripts and papers. A century after his death, Angelo Maria Bandini noticed a record of payment of 25 scudi to the bricklayer, which led to the discovery of the stashed papers. (ibid. p.989))

Gergo is also mentioned in a letter from Galileo's old friend Benedetto Castelli of 26 May 1640. This time, Marcus and Findlen (2019) considers they were gossiping about a post (lectureship of mathematics) in Pisa. (ibid. p.984-985)

I did not understand the beginning of your letter, the part that you wrote for me to understand through gergo.


Hannah Marcus and Paula Findlen, "Deciphering Galileo: Communication and Secrecy before and after the Trial", Renaissance Quarterly, FALL 2019, vol.72, no.3, pp.953-995

Edward Rosen (edited and translated) (1965), "Kepler's Conversation with Galileo's Sidereal Messenger", The Sources of Science (pdf)

Galileo Galilei's Anagram, Rutgers Physics

©2023 S.Tomokiyo
First posted on 1 July 2023. Last modified on 1 July 2023.
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