Mental Models from History
12 Sayings Checked Against the Sources

Plenty of the thinking tools people quote are named after a battle, a ruler or a scandal. The name travels; the source usually does not. Here are twelve, checked against the ancient texts, letters and archives they came from. English after Latin, Greek, Spanish, French or Chinese is our translation unless a translator is named. The companion pages are Mental models, checked and Mental models from philosophy.

1. A Pyrrhic victory

Partly true The remark is reported, not recorded. Plutarch, in his Life of Pyrrhus, writes that “we are told that Pyrrhus said to one who was congratulating him on his victory, ‘If we are victorious in one more battle with the Romans, we shall be utterly ruined.’” (tr. Perrin). Diodorus gives a different wording: “If I win a victory in one more battle with the Romans, I shall not have left a single soldier of those who crossed over with me”. Plutarch’s two sources disagree about the battle itself, and Diodorus says the proverb for such a win was not “Pyrrhic” at all: “A ‘Cadmean victory’ is a proverbial expression.”

Both writers explain it the same way, and it is about replacement more than the dead. Pyrrhus “had lost a great part of the forces with which he came”, while the Romans, in Diodorus’s words, “though defeated, were in no way humbled, since their dominion was so great”. The tool: count what you can replace, not only what you lost.

2. Crossing the Rubicon

Partly true as the classic snap point of no return. Caesar did cross; Suetonius has him overtake “his cohorts at the river Rubicon, which was the boundary of his province”. But Caesar’s own Civil War does not mention the river: book 1 simply says he “set out for Ariminum with that legion” (Ariminum cum ea legione proficiscitur).

The famous scene comes from later writers, and it is a scene of hesitation. Plutarch says Caesar “communed with himself a long time in silence as his resolution wavered back and forth”, talked it over with friends “among whom was Asinius Pollio”, and crossed at last “as if abandoning calculation and casting himself upon the future”. Suetonius needs a supernatural sign to tip him: “a being of wondrous stature and beauty, who sat and played upon a reed”. For the words he is supposed to have said, see Latin phrases, checked.

3. The sword of Damocles

Partly true as “a danger hanging over you”. The story is in Cicero’s Tusculan Disputations (5.61–62), and it is about the tyrant, not the guest. Damocles, “one of his flatterers”, praises the wealth of Dionysius of Syracuse; Dionysius seats him at a feast and “ordered a bright sword to be let down from the ceiling, suspended by a single horse-hair” (tr. Yonge; the Latin says only saeta equina, a horse-hair). Damocles at last begs “to go, for that now he had no desire to be happy”.

Cicero spells out the point: “Does not Dionysius, then, seem to have declared there can be no happiness for one who is under constant apprehensions?” The fear on display is the ruler’s own. Cicero names no earlier source for the story. The tool: before envying a position, ask what its holder has to live with.

4. Cutting the Gordian knot

Disputed that Alexander cut it with his sword. The ancient accounts split. Arrian’s Anabasis (2.3, tr. Chinnock) says some report that “he struck the cord with his sword and cut it through”, but “Aristobulus says that he pulled out the pin of the wagon-pole, which was a wooden peg driven right through it, holding the cord together.” Aristobulus is one of Arrian’s main sources, chosen “because he served under king Alexander in his expedition”. Arrian then declines to choose: “How Alexander performed the feat in connection with this cord, I cannot affirm with confidence.”

Plutarch says “most writers” tell the sword version, and gives the pin version to Aristobulus too. The prize differs by source: to be “the ruler of Asia” in Arrian, “king of the whole world” in Plutarch. Either way the solution is a sideways one; only the swordstroke is uncertain.

5. Fabian strategy

True that Fabius Maximus avoided pitched battle with Hannibal and wore him down. Polybius says he made “the safety of the army under his command his first and chief aim, adhered steadfastly to this purpose”. It was unpopular at the time: “At first, it is true, he was despised for this, and gave people occasion to say that he was playing the coward”, and in Plutarch “the soldiers railed at Fabius and scornfully called him Hannibal’s pedagogue”. The poet Ennius praised him in a line Cicero quotes: “Unus homo nobis cunctando restituit rem” — one man, by delaying, restored the state for us.

The modern version, wait and then strike hard, comes from somewhere else. The Fabian Society, named in January 1884 “in allusion to the victorious policy of Fabius Cunctator”, printed on its first tract a motto saying that “when the time comes you must strike hard, as Fabius did”. Its own historian, Edward Pease, wrote that the mottoes, “though printed as quotations, are not to be discovered in any history”, and noted: “It has been pointed out by Mr. H.G. Wells, and by others before him, that Fabius never did strike hard”.

6. Burning the boats

Myth that Hernán Cortés burned his ships. In his second letter to the emperor he says he decided, “on the pretext that they were unseaworthy”, to have “the said ships beached” (tr. MacNutt), so that “everybody lost hope of ever leaving the country”. Bernal Díaz, who was there, says the soldiers proposed running the vessels ashore “in order at once to cut off all possibility of further mutiny”, adds that “the pilots and sailors would be of greater use to us” as soldiers, and suspects “the idea of destroying our vessels originated with Cortes himself”. Díaz’s soldiers even compare themselves to Caesar: “as the die had been cast, and we, with Caesar, when he had passed the Rubicon, had now no choice left”.

Unverified that Tariq ibn Ziyad burned his ships on landing in Spain. The story rests on later reports. Pascual de Gayangos, who translated al-Maqqari’s history, notes that Tariq “like Cortés, is reported to have set fire to his fleet”, and says the claim “may reasonably be questioned”.

True for the oldest of the three versions here. Sima Qian’s Shiji (chapter 7) says Xiang Yu led his army across a river, and then 皆沈船，破釜甑 — they sank all the boats and smashed the cooking pots — carrying three days’ food, “to show the soldiers they must die, with no thought of returning”. The Art of War has the same image for a general deep in enemy country: “He burns his boats and breaks his cooking-pots” (chapter 11, tr. Giles). The tool is about commitment, but the case with the fullest record is a warning too: Cortés wrote that the aim was to stop his own men leaving, and Díaz says he arranged it so that, if the owners wanted paying, “he could throw the blame on us”.

7. Hobson’s choice

Partly true Thomas Hobson was a real “carrier of Cambridge”, who died there in January 1631, and Milton wrote comic epitaphs for him. The stable story was printed eighty-one years later, in a letter in The Spectator No. 509 of 14 October 1712. It says Hobson kept “forty good Cattle” and made each customer “take the Horse which stood next to the Stable-Door; so that every Customer was alike well served according to his Chance”.

Two details in the letter are worth knowing. It calls him “Tobias Hobson”. And it says the phrase was already being used, “by vulgar Error”, for a man “reduced to an Extremity”; its own sense was fair turns from plenty. It also glosses the phrase as a choice “forced upon you”. The Dictionary of National Biography is cautious: the stable rule “is said to have given rise to the proverb”, and the claim that he was the first to hire out horses is “asserted very doubtfully”.

8. The cobra effect

Unverified that British officials in Delhi paid a bounty for dead cobras and people bred cobras to claim it. The phrase is the title of a 2001 German book on economic policy by Horst Siebert, Der Kobra-Effekt. No one we could find has produced a colonial record, a date or an official for the Delhi story. We did not search Indian colonial records on snake bounties in general.

True for the documented case, which is about rats. The historian Michael G. Vann, who found the records in the French colonial archives, says that the city’s rat records run from April to July 1902, and that officials in Hanoi put out a bounty “paying a few cents for each rat tail”. People responded by “cutting off their tails to collect the bounty, and then letting them go free to breed more rats”, and officials “also found a smuggling network bringing rats” into the city. It is the incentive version of Goodhart’s law: reward the measure, and people produce the measure.

9. The Thucydides trap

Disputed as a reading of Thucydides. The phrase is Graham Allison’s, not Thucydides’. In The Atlantic in September 2015 he calls it “the Greek historian’s metaphor” and reports that a team of his at Harvard’s Belfer Center found that “in 12 of 16 cases over the past 500 years, the result was war”, while adding: “War, however, is not inevitable.”

The sentence behind it is Thucydides 1.23.6. Richard Crawley’s translation gives “made war inevitable”; the Greek verb, anankasai, means forced or compelled, and Thucydides offers the growth of Athens and Sparta’s fear as the “truest cause” but the one “least spoken of”. Not every classicist reads the passage the way political scientists do: a 2025 article in Classical Antiquity argues that Thucydides “suggests that the war might have started through a process of self-fulfilling prophecy”, and that this “challenges not only the idea of the” trap. The case count is Allison’s team’s own. This page gives no forecast.

10. The Lindy effect

Partly true as “the longer something has lasted, the longer it will last”. The name comes from Lindy’s, a delicatessen, and a 1964 New Republic piece by Albert Goldman listed in the magazine’s index as “Lindy’s law”, which, as Toby Ord summarises it, was “about how the future career length of a comedian might be predicted from their past exposure”. In 1982 Benoît Mandelbrot called his rule “Lindy’s Law” in honour of Goldman’s anecdote, and “the idea was developed by Nassim Taleb (2012) in his book, Antifragile”, as Ord puts it. Ord adds: “It is not clear whether Goldman, or the denizens of Lindy’s Deli he describes, were really describing the same principle as Mandelbrot.”

It is a pattern for some things, not a law for all: Ord notes that “the empirical distribution of human lifespans doesn’t exhibit even a broad Lindy effect”. A person who has lived ninety years does not have ninety more.

11. Cincinnatus

Partly true as “the farmer who left his plough, saved Rome and gave up power”. The story is in Livy (book 3), who tells it as a lesson for “those who despise everything human beside riches”. Livy does not know what Cincinnatus was doing when the envoys arrived: “whether digging a ditch and leaning on his spade, or ploughing”, only that he was, “as is agreed”, at farm work. He farmed four iugera across the Tiber, and Livy has already told us why he was poor: money for his son’s skipped bail was, in Spillan’s translation, “rigorously exacted” from the father, who sold everything and lived “in a solitary cottage on the other side of the Tiber”.

He did not resign the moment the war was won. Livy says he “would have laid down his office, had not the assembly for the trial of Marcus Volscius, the false witness, detained him”; Volscius had testified against his son. “Quintius laid down his dictatorship on the sixteenth day, having received it for six months.”

12. Potemkin villages

Disputed that Potemkin built fake village fronts to fool Catherine II on her journey to the Crimea. The story was already going round during the journey: the Prince de Ligne, who was on it, called the tale of cardboard villages carried along the route “le conte ridicule”. It was later printed in a German memoir of Potemkin (English second edition, 1813), which hedges the fake fronts: “It has even been asserted that the most distant buildings were unfinished, and had merely a front.” The same book does state as fact that peasants were moved “from one spot to the other (frequently in the night)”. It rejects a related story about herds moved at night (“The shores of the Dnieper are, besides, rich enough in cattle not to need such a resource”) and concludes that “Envy, which fastens itself upon great men, has magnified what was but show, and diminished what was real”.

Two people on the journey describe something in between. The Prince de Ligne wrote that there were often “des villes sans rues, des rues sans maisons et des maisons sans toit, portes ni fenêtres” — towns without streets, streets without houses, and houses without roofs, doors or windows. The French ambassador, the comte de Ségur, says towns and villages were “tellement ornés et déguisés par des arcs de triomphe” — so adorned and disguised with triumphal arches — that the illusion turned them “into superb cities”. That is a staged tour of real, partly unfinished settlements. We did not read modern scholarship on the question, so the verdict stays open.

Our reading

The ancient writers were usually more cautious than the sayings named after their stories: “we are told”, “I cannot affirm with confidence”, “whether digging a ditch… or ploughing”. The versions that circulate keep the drama and drop the hedge. When a thinking tool comes with a famous story attached, the story is worth checking before the tool is.

Sources

• Plutarch, Lives of Pyrrhus, Caesar, Alexander and Fabius Maximus, tr. B. Perrin (Loeb); Diodorus Siculus, book 22 (Loeb).
• Suetonius, Divus Julius, tr. J. C. Rolfe (Loeb); Caesar, Bellum Civile 1 (Latin).
• Cicero, Tusculan Disputations 5, Latin and tr. C. D. Yonge; Cicero, De Senectute 10 (quoting Ennius).
• Arrian, Anabasis of Alexander 2.3, tr. E. J. Chinnock.
• Polybius, Histories 3.89 (Loeb); E. R. Pease, The History of the Fabian Society.
• Hernán Cortés, second letter, in Letters of Cortes, tr. F. A. MacNutt; Bernal Díaz del Castillo, Memoirs, tr. J. I. Lockhart; al-Maqqari, tr. P. de Gayangos, The History of the Mohammedan Dynasties in Spain; Sima Qian, Shiji 7.
• The Spectator No. 509; T. Cooper, “Hobson, Thomas”, Dictionary of National Biography.
• Deutsche Nationalbibliothek catalogue, H. Siebert, Der Kobra-Effekt; M. G. Vann, French Colonial History 4 (2003); I. Franceschini, “The Great Hanoi Rat Hunt: A Conversation with Michael G. Vann”, Made in China Journal.
• Thucydides 1.23.6, Greek text and tr. R. Crawley; G. Allison, The Atlantic, 24 September 2015; D. Sutton, “Thucydides’ Ambiguous Trap”, Classical Antiquity 44 (2025).
• The New Republic index, vol. 150; T. Ord, “The Lindy Effect”, arXiv (2023).
• Livy, Ab Urbe Condita 3, Latin and tr. D. Spillan.
• Memoirs of Prince Potemkin, translated from the German, 2nd ed. (1813); comte de Ségur, Mémoires, vol. 2, with letters of the Prince de Ligne.

Checked September 2026.

Related: Mental models, checked · Mental models from philosophy · Latin phrases, checked