"Forty Days and Forty Nights"

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The old hymn and blues song of that title have been very much on my mind during the last couple of months.

George Hunt Smyttan (1856)

Forty days and forty nights
You were fasting in the wild;
Forty days and forty nights,
Tempted, and yet undefiled….

Muddy Waters (1956)

Forty days and forty nights, since my baby left this town
Sun shinin' all day long, but the rain keep falling down
She's my life I need her so, why she left I just don't know….

These are very different kinds of songs, yet they are both focused on a period of forty days and forty nights.  I've been thinking about these songs a lot in the current climate of far-reaching quarantines against the novel coronavirus epidemic centered on Wuhan, Hubei Province, China.

James Grundvig (personal communication) points out:

The word root of "quarantine" is derived from the number 40, as in 40 days. Now think of the Book of Genesis and the 40 days of Noah's Flood and the New Testament with Jesus resisting temptation of Satan for 40 days in the desert. These numbers are not an accident or a coincidence.

James brought up the question of "40 days" in the context of what is the appropriate length of a quarantine against a disease like the novel coronavirus that is raging across much of the world.  A very common length of quarantine that is being imposed on travellers who are suspected of having been exposed to the virus is 14 days, but many people who are tracking the virus think that this is an inadequate length of time, since we are still uncertain about the incubation period of the disease.  Furthermore, some individuals who have gone through a 14-day quarantine end up showing symptoms of the disease after being released.

Let's look at the history of the word "quarantine" to see what it may tell us about the rationale for a forty day period of isolation.

Italian quarantena, from Venetian dialectal Italian, quarantine of a ship (so called because the length of the quarantine was typically forty days), from Old Italian quarantina, period of forty days (such as one designated for fasting or penance), from quaranta, forty, from Latin quadrāgintā; see kwetwer- in Indo-European roots.

[American Heritage Dictionary of the English Language, 5th ed.]


quarantine (n.)

1660s, "period a ship suspected of carrying disease is kept in isolation," from Italian quarantina giorni, literally "space of forty days," from quaranta "forty," from Latin quadraginta "forty," which is related to quattuor "four" (from PIE root *kwetwer- "four"). So called from the Venetian policy (first enforced in 1377) of keeping ships from plague-stricken countries waiting off its port for 40 days to assure that no latent cases were aboard. Also see lazaretto. The extended sense of "any period of forced isolation" is from 1670s.

Earlier in English the word meant "period of 40 days in which a widow has the right to remain in her dead husband's house" (1520s), and, as quarentyne (15c.), "desert in which Christ fasted for 40 days," from Latin quadraginta "forty."



Etymology 1

Directly from Latin quadraginta (forty)


quarantine (plural quarantines)

    1. A desert in which Christ fasted for 40 days according to the Bible
    2. A grace period of 40 days during which a widow has the right to remain in her dead husband's home, regardless of the inheritance

Etymology 2

From Italian quarantina (forty), from quarantina giorni (forty days), (the period Venetians customarily kept ships from plague-ridden countries waiting off port), from quaranta (forty), from Latin quadraginta (forty)


quarantine (countable and uncountable, plural quarantines)

    1. A sanitary measure to prevent the spread of a contagious plague by isolating those believed to be infected.
    2. Such official detention of a ship at or off port due to suspicion that it may be carrying a contagious disease aboard.
    3. A certain place for isolating persons suspected of suffering from a contagious disease.
    4. A certain period of time during which a person is isolated to determine whether they've been infected with a contagious disease.
    5. (by extension) Any rigorous measure of isolation, regardless of the reason.
    6. A record system kept by port health authorities in order to monitor and prevent the spread of contagious diseases.
    7. (computing) A place where email messages or other files which are suspected of harboring a virus are stored.


It is striking how a period of extreme isolation or privation that was known already in biblical times later evolved and extended to refer to periods of different length and to phenomena as diverse as a widow's right to remain in her dead husband's home and where to store problematic files in one's computer.


Selected readings

"Chinese coronavirus linguistic war" (2/22/20)

"The PRC censors its own national anthem" (2/9/20)

"Winnie the Flu" (2/24/20)

"Sino-Manchu seals of the Xicom Emperor" (2/12/20)

"History of Quarantine", Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Global Migration and Quarantine (DGMQ) (1/10/12)


  1. Gene hill said,

    February 29, 2020 @ 7:43 am

    I think it would be better to examine the number 40 (Mem) I recall from my studies of the Kabbalah that mem used by Secular writers is an indefinite number meaning more than a mortal can conceive. Ali Baba and the forty thieves.
    The number 40 is of great significance, not only in mysticism, but also in the simple understanding of the Torah. For example, the 40 days that Moses was in heaven to receive the Torah, 40 days of the Flood. In addition, 40 relates to the 40 days from the beginning of pregnancy until the fetus is well formed. This is a very important stage in pregnancy.
    40 is also the value of the letter mem, which means water. This is why 40 refers both to the Torah, which is water, and also to the Flood. In the future the flood will be a positive concept–the flood of knowledge of G-d. This is the inner soul of the Torah which will fill the earth just as water covers the seabed. Water covering the seabed is the secret of the letter mem and the number 40.
    In addition, when one becomes 40 years old he receives the deepest measure of understanding, in order to understand the Torah. This is especially in order to understand the deep intention that his teacher had that he was not able to comprehend initially. At the age of 40 one understands his teacher’s inner meaning.
    It would be most worthwhile for you to see the Hebrew Letters Book on the letter mem, which provides more information on the number 40.

  2. Victor Mair said,

    February 29, 2020 @ 8:08 am

    "All You Zombies" – Hooters (lyrics)


    Holy Moses met the Pharaoh
    Yeah, he tried to set him straight
    Looked him in the eye,
    "Let my people go!"

    Holy Moses on the mountain
    High above the golden calf
    Went to get the Ten Commandments
    Yeah, he's just gonna break 'em in half!

    All you zombies hide your faces,
    All you people in the street,
    All you sittin' in high places,
    The pieces gonna fall on you

    No one ever spoke to Noah,
    They all laughed at him instead
    Workin' on his ark,
    Workin' all by himself

    Only Noah saw it comin',
    Forty days and forty nights,
    Took his sons and daughters with him,
    Yeah, they were the Israelites!

    [There are four more quatrains, also worth reading]

  3. Victor Mair said,

    February 29, 2020 @ 8:38 am

    Thanks for the great comments on mem.

    This is interesting:


    Mem (also spelled Meem, Meme, or Mim) is the thirteenth letter of the Semitic abjads, including Hebrew mēm מ, Aramaic Mem Mem.svg, Syriac mīm ܡܡ, Arabic mīm م and Phoenician mēm Phoenician mem.svg. Its value is [m].

    The Phoenician letter gave rise to the Greek mu (Μ), Etruscan M, Latin M, and Cyrillic М.

    Mem is verisimilar coming from Proto-Semitic *maʾ-/*may-. It is believed that the Phoenician word for “water”, mem (Phoenician mem.png) is a morphed and simplified Egyptian hieroglyphic symbol for water.




  4. Philip Taylor said,

    February 29, 2020 @ 8:47 am

    Well, that is the first time (in nearly 73 years) that I have encountered the word "verisimilar" — "verisimilitude" frequently, but "verisimilar" never before. One lives and learns.

    But in the Wikipedia entry cited, should it not be the adverb "verisimilarly" ?

  5. Victor Mair said,

    February 29, 2020 @ 8:58 am

    Besides mem / 40, another magic number with wide-ranging implications and applications is 72, for which see pp. 70-72 and 212n46 of Victor H. Mair, "The North(west)ern Peoples and the Recurrent Origins of the 'Chinese' State", in Joshua A. Fogel, The Teleology of the Modern Nation-State: Japan and China (Philadelphia: University of Pennsylvania Press, 200), pp. 46-84, 205-217.

  6. Eric Sadoyama said,

    February 29, 2020 @ 9:19 am

    My favorite Hooters song

  7. Doctor Science said,

    February 29, 2020 @ 9:38 am

    Does Chinese have an old word for "quarantine"? Was it every (pre-19th C) a public health practice? The only references I have been able to find are to Manchu attempts to protect *themselves* against smallpox.

  8. cameron said,

    February 29, 2020 @ 11:05 am

    The use of "quarantine" to mean a period when a widow may remain in her husband's house regardless of inheritance must be connected with the various uses of forty-day intervals in connection with mourning more generally. The fortieth day after death is an occasion for a memorial service in the Eastern Orthodox churches and also in various middle eastern countries.

    During the Iranian Revolution of 1978-79 the major episodes of street unrest often took place at forty-day intervals, as people would take to the streets to commemorate the killings of protesters at the last such occasion.

    The Feast of the Ascension occurs on the fortieth day of Easter, and is no doubt also connected with the traditional forty-day mourning period.

  9. Anthony said,

    February 29, 2020 @ 3:24 pm

    There's also "The Forty Days of Musa Dagh" (Franz Werfel). I read it many years ago (40?) and don't remember if forty is significant.

  10. J.W. Brewer said,

    February 29, 2020 @ 3:56 pm

    Like pretty much any text worthy of serious scholarly attention, "All You Zombies" is extant in multiple variants/editions/redactions. I personally take the view that the pristine ur-text is that transcribed in the field by ethnographers (not sure if there was any institutional association with UPenn) on April 11, 1981 in Cherry Hill, N.J., which can be found here: https://www.youtube.com/watch?v=N6iaF9SWMU4.

  11. Jerry Friedman said,

    February 29, 2020 @ 6:33 pm

    No mention that Lent, which I believe is currently happening (at least in the West), is forty days long?

    Or that "All You Zombies" took its title from a story by Robert A. Heinlein? My favorite of his, as it happens.

  12. Timothy Rowe said,

    February 29, 2020 @ 9:34 pm

    On "verisimilar" vs. "verisimilarly": http://www.macmillandictionaryblog.com/flat-adverbs-are-exceeding-fine

  13. AntC said,

    February 29, 2020 @ 11:39 pm

    A very common length of quarantine [for COVID-19] that is being imposed on travellers who are suspected of having been exposed to the virus is 14 days, but many people who are tracking the virus think that this is an inadequate length of time, since we are still uncertain about the incubation period of the disease.

    Yikes! I've just returned from Taiwan (~40 cases, 1 death, population ~23 million) to NZ (1 case, no deaths, ~4.5 million), to encounter vague/lackadaisical advice: voluntary self-isolation for 14 days; or maybe just avoid crowds; or maybe Don't Panic Carry On — depending which government agency I listen to.

    I'm half way through 14 days of avoiding breathing near people; and manically hand-sanitising everything. Don't think I could last 40 days at this: I need to go hang out in a coffee shop. The worst is the alarmed stares I get at a gweilo wearing a face mask. NZ'ers have just about got used to the Chinese community wearing them here. In Taiwan they were de rigeur.

  14. David Morris said,

    March 1, 2020 @ 12:38 am

    We got both the modern 'You were fasting' and the traditional 'Thou wast fasting' this morning. The choir had the modern version and the congregation had the traditional one. Some verses are more similar (the first verse differs only by You were/Thou wast) and some are very different. The sermon mentioned some of the points in this post.

  15. Victor Mair said,

    March 1, 2020 @ 2:28 am

    @David Morris

    I wonder if your pastor actually read this post before composing his sermon. It is amazing how many people regularly consult Language Log year after year. It is always tremendously gratifying when they find something we write here to be of value to them.

  16. Keith said,

    March 1, 2020 @ 6:02 am

    I remember from R.E. class in junior school in the UK that we were told that the Hebrew and Aramaic texts used the equivalent of the English word "forty" simply to mean "many" or "a great many".

    Oh, and there's a song "Forty Days and Forty Fights" by Badly Drawn Boy.

  17. Chris Button said,

    March 1, 2020 @ 6:41 am

    @ Victor Mair

    Regarding "mem", any chance we could get a teaser of any of your tiangan dizhi thoughts?

  18. Geoff M. said,

    March 1, 2020 @ 7:43 am

    As it happens, at the high mass I attended on Ash Wednesday we both sang that hymn and heard a sermon which made the connexion between Quadragesima and quarantine, with reference to COVID-19.

  19. Victor Mair said,

    March 1, 2020 @ 8:00 am

    From Alan Kennedy:

    "Forty acres and a mule" was a radical post-Civil War policy of redistributing land in the South as compensation for former slaves.

    Another old American term relating to acres is "back forty":


  20. Coby Lubliner said,

    March 1, 2020 @ 8:25 am

    In Romance languages the word for 'lent' is derived from the Latin quadragesima (Spanish cuaresma, French carême etc.), meaning 'fortieth' (day).

  21. cameron said,

    March 1, 2020 @ 2:02 pm

    The traditional "40 acres" probably derives from the fact that an acre is 1/640 of a square mile.

  22. William Morder said,

    March 1, 2020 @ 4:23 pm

    40 is the special number of the Sumerian god Enki (known to the Babylonians as Ea), whose element is water. I believe that S.N. Kramer mentions this in *Sumerian Mythology*; otherwise, it is in another of his books. I am pretty sure that I've come across this detail in other sources, too. I had quite forgotten the connection with the Semitic letter *mem* (in its various forms), which is has the value of number 40, as well.

    Also, 40 days is not quite 6 weeks (made up of 7-day weeks, which was not always universal); 42 days is rounded off to 40, in the same manner as 72 was often rounded off to 70. A vestige of this survives in the name of the Septuagint, the Seventy, which actually refers to 72: the members of the Sanhedrin, I believe, who were 71+1 or 70+2, the leftovers being one or both of the prophets Enoch and Elijah.

  23. Victor Mair said,

    March 1, 2020 @ 6:20 pm

    From Thomas K. Mair:

    I might add a couple things. A fast of 40 days is close to impossible, and could have deadly consequences. So it's a true sage only that could achieve it. In my lifetime, I only know of 1 person who achieved a 30 day fast, though he did drink fruit juices during that fast.

  24. Victor Mair said,

    March 1, 2020 @ 6:22 pm

    Since several of the comments have mentioned Lent and fasting in connection with the notion of "forty", I thought it might be good to look into the relevant terms for these activities in various languages:


    The English word Lent is a shortened form of the Old English word lencten, meaning "spring season", as its Dutch language cognate lente (Old Dutch lentin) still does today. A dated term in German, Lenz (Old High German lenzo), is also related. According to the Oxford English Dictionary, 'the shorter form (? Old Germanic type *laŋgito- , *laŋgiton-) seems to be a derivative of *laŋgo- long … and may possibly have reference to the lengthening of the days as characterizing the season of spring'. The origin of the -en element is less clear: it may simply be a suffix, or lencten may originally have been a compound of *laŋgo- 'long' and an otherwise little-attested word *-tino, meaning 'day'.

    In languages spoken where Christianity was earlier established, such as Greek and Latin, the term signifies the period dating from the 40th day before Easter. In modern Greek the term is Σαρακοστή (Sarakostí), derived from the earlier Τεσσαρακοστή (Tessarakostí), meaning "fortieth". The corresponding word in Latin, quadragesima ("fortieth"), is the origin of the terms used in Latin-derived languages and in some others. Examples in the Romance language group are: Catalan quaresma, French carême, Galician coresma, Italian quaresima, Occitan quaresma, Portuguese quaresma, Romanian păresimi, Sardinian caresima, Spanish cuaresma, and Walloon cwareme. Examples in non-Latin-based languages are: Albanian kreshma, Basque garizuma, Croatian korizma, Irish carghas, Swahili kwaresima, Tagalog kuwaresma, and Welsh c(a)rawys.

    In other languages, the name used refers to the activity associated with the season. Thus it is called "fasting period" in Czech (postní doba), German (Fastenzeit), and Norwegian (fasten/fastetid), and it is called "great fast" in Arabic (الصوم الكبير – alsuwm alkabir, literally, "the great fasting"), Polish (wielki post), Russian (великий пост – vieliki post), and Ukrainian (великий піст – velyky pist). Romanian, apart from a version based on the Latin term referring to the 40 days (see above), also has a "great fast" version: postul mare. Dutch has three options, one of which means fasting period, and the other two referring to the 40-day period indicated in the Latin term: vastentijd, veertigdagentijd and quadragesima, respectively.


  25. E Bruce Brooks said,

    March 1, 2020 @ 9:14 pm

    Forty in the oldest Biblical usages is a period of purification before approaching a sacred space (Moses on the mountain), transferred to the purification of Israel in the Wilderness before entering the Promised Land. It seems quite likely to derive from an ancient but secular period of isolation of those impure, or suspected to be impure (carrying a disease).. I would be interested to hear from a medical historian, and/or an anthropologist.

    Physiologically, fasting (avoiding all food; I didn't say water) for forty days and forty nights will at least in some cases produce a physical state something like meditation; entering a different psychic state (or, one might think, realm). This too amounts to an entry procedure.

  26. Andreas Johansson said,

    March 1, 2020 @ 10:49 pm

    Is "Etymology 1" really directly from Latin? It certainly looks suspiciously like it's undergone the same Romance changes as "Etymology 2".

  27. anhweol said,

    March 2, 2020 @ 1:14 am

    The Welsh is actually Garawys or Grawys, which is odd as initial C as above would be expected in the basic form. It's also masculine, which is not so surprising as Latin borrowings often switch gender. If it was feminine once, it would have mutated the intial letter after the definite article to produce 'y Garawys'. If that was then reinterpreted as a sequence of definite article followed by (unmutated) masculine noun, I suppose it could have generated a new basic form with G. I have no idea whether that is what really happened.

  28. Philip Anderson said,

    March 2, 2020 @ 2:19 am

    All the early forms (c13th onwards) show ‘garawys’ or ‘grawys’, except for an ‘arawys’ (which shows that garawys was taken to be the unlenited form), but ‘Caraŵys’ is conjectured to have been the original.

  29. Alyssa said,

    March 2, 2020 @ 10:54 am

    14 days was an initial estimate of the maximum incubation period of the virus, but evidence over time has shown that it is probably inadequate. As far as I'm aware, all authorities are sticking to a 14 day quarantine, likely for reasons of human nature: Two weeks is about the longest period of time you can get most people to comply with a self-quarantine. Requesting a longer quarantine would just result in less compliance, with a net increase in the amount of infectious people running around.

  30. Chips Mackinolty said,

    March 9, 2020 @ 5:26 pm

    Given the overnight announcement that Italy is imposing nation-wide travel restrictions, we are perhaps witnessing the revival of the origin of the word quarantena. Venezia, of course, is now virtually deserted.

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