Aweek is a unit of time equal to sevendays. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days ofworship. Weeks are often mapped against yearlycalendars. There are just over 52 weeks in ayear. The term "week" may also be used to refer to a sub-section of the week, such as theworkweek and weekend.
Ancient cultures had different "week" lengths, including ten days in Egypt and an eight-day week forEtruscans. The Etruscan week was adopted by theancient Romans, but they later moved to a seven-day week, which had spread across Western Asia and the Eastern Mediterranean due to the influence of the Christian seven-day week, which is rooted in theJewish seven-day week. In AD 321, EmperorConstantine the Great officially decreed a seven-day week in the Roman Empire, including making Sunday a public holiday.[1][2] This later spread across Europe, then the rest of the world.
In English, thenames of the days of the week areMonday,Tuesday,Wednesday,Thursday,Friday,Saturday andSunday. In many languages, including English, the days of the week are named after gods orclassical planets. Saturday has kept its Roman name, while the other six days use Germanic equivalents. Such a week may be called aplanetary week (i.e., a classical planetary week).[4] Certain weeks within ayear may be designated for a particular purpose, such asGolden Week in China andJapan. More informally, certain groups may advocateawareness weeks, such asNational Family Week in Canada, which are designed to draw attention to a certain subject or cause.
Cultures vary in which days of the week are designated the first and the last, though virtually all have Saturday, Sunday or Monday as the first day. TheGeneva-based ISO standards organization uses Monday as the first day of the week in itsISO week date system through the internationalISO 8601 standard.[a] Most of Europe and China consider Monday the first day of the (work) week, while North America, South Asia, and many Catholic and Protestant countries, consider Sunday the first day of the week. It is also the first day of the week in almost all of the Arabic speaking countries.[contradictory] This is culturally and historically the case since in Arabic Sunday is referred to as "Yaom Al'Ahad" which literally means "The first day".[5][6] Other regions are mixed, but typically observe either Sunday or Monday as the first day.[7]
The threeAbrahamic religions observe different days of the week as their holy day.Jews observe theirSabbath (Shabbat) on Saturday, the seventh day, from sundown Friday to sundown Saturday, in honor of God'screation of the world in six days and then resting on the seventh.[8] MostChristians observe Sunday (theLord's Day), the first day of the week in traditional Christian calendars, in honor of theresurrection of Jesus.[9]Muslims observe their"day of congregation", known asyaum al-jum`ah, on Friday because it was described as a sacred day of congregational worship in theQuran.[10]
The English wordweek comes from theOld Englishwice, ultimately from aCommon Germanic*wikōn-, from a root*wik- "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of theRoman calendar, perhaps "succession series", as suggested byGothicwikō translatingtaxis "order" inLuke 1:8.
The seven-day week is named in many languages by a word derived from "seven". Thearchaismsennight ("seven-night") preserves the old Germanic practice of reckoning time by nights, as in the more commonfortnight ("fourteen-night").[11]Hebdomad andhebdomadal week both derive from theGreekhebdomás (ἑβδομάς, "a seven").Septimana is cognate with theRomance terms derived fromLatinseptimana ("seven mornings").
1 Gregorian calendar year = 52 weeks + 1 day (2 days in aleap year)
1 week =1600⁄6957 ≈ 22.9984% of an average Gregorian month
In aGregorian mean year, there are 365.2425 days, and thus exactly52+71⁄400 or 52.1775 weeks (unlike theJulian year of 365.25 days or52+5⁄28 ≈ 52.1786 weeks). There are exactly 20,871 weeks in 400 Gregorian years, so 26 November 1625 was a Wednesday just as was 26 November 2025.
Relative to the path of theMoon, a week is 23.659% of an averagelunation or 94.637% of an average quarter lunation.
Historically, the system ofdominical letters (letters A to G identifying the weekday of the first day of a given year) has been used to facilitatecalculation of the day of week.The day of the week can be easily calculated given a date'sJulian day number (JD, i.e. the integer value atnoonUT):Adding one to theremainder after dividing the Julian day number by seven (JDmodulo 7 + 1) yields that date'sISO 8601 day of the week. For example, the Julian day number of 26 November 2025 is 2461006. Calculating2461006 mod 7 + 1 yields 3, corresponding to Wednesday.[12] In 1973,John Conway devised theDoomsday rule for mental calculation of the weekday of any date in any year.
An Italiancameo bracelet representing the days of the week by their eponymous deities (mid-19th century,Walters Art Museum)Schematic comparison of the ordering of the classical planets (arranged in a circle) and the sequence of days in the week (forming a {7/3}heptagram within the circle).
The days of the week were named for the sevenclassical planets, which included the Sun and Moon. This naming system persisted alongside an "ecclesiastical" tradition of numbering the days inecclesiastical Latin beginning withDominica (theLord's Day) as the first day. The Greco-Roman gods associated with the classical planets were rendered in theirinterpretatio germanica at some point during the late Roman Empire, yielding the Germanic tradition of names based on indigenous deities.
The ordering of the weekday names is not the classical order of the planets (by distance in theplanetary spheres model, which is Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn); nor, equivalently, by their apparent speed of movement in the night sky. Instead, theplanetary hours systems resulted in succeeding days being named for planets that are three places apart in their traditional listing. This characteristic was apparently discussed inPlutarch in a treatise written in c. 100 CE, which is reported to have addressed the question ofWhy are the days named after the planets reckoned in a different order from the actual order? (the text of Plutarch's treatise has been lost).[13]Dio Cassius (early 3rd century) gives two explanations in a section of hisHistoria Romana after mentioning the Jewish practice of sanctifying the day called the day ofKronos (Saturday).[14]
An ecclesiastical, non-astrological, system of numbering the days of the week was adopted in Late Antiquity. This model also seems to have influenced (presumably viaGothic) the designation of Wednesday as "mid-week" inOld High German (mittawehha) andOld Church Slavonic (срѣда, srěda, literally,middle day). Old Church Slavonic may have also modeled the name of Monday,понєдѣльникъ (literally,the day after Sunday), after the Latinferia Secunda.[15]
Circular diagrams showing the division of the day and of the week, from aCarolingian ms. (Clm 14456 fol. 71r) ofSt. Emmeram Abbey. The week is divided into seven days, and each day into 24 hours, 96puncta (quarter-hours), 240minuta (tenths of an hour) and 960momenta (40th parts of an hour).
The earliest evidence of an astrological significance of a seven-day period is a decree of kingSargon of Akkad around 2300 BCE. Akkadians venerated the number seven, and the key celestial bodies visible to the naked eye numbered seven (the Sun, the Moon and the five closest planets).[18]
Gudea, the priest-king ofLagash inSumer during theGutian dynasty (about 2100 BCE), built a seven-room temple, which he dedicated with a seven-day festival. In the flood story of theAssyro-BabylonianEpic of Gilgamesh, the storm lasts for seven days, the dove is sent out after seven days (similarly in Genesis), and theNoah-like character ofUtnapishtim leaves the ark seven days after it reaches the firm ground.[c]
Counting from thenew moon, the Babylonians celebrated the 7th, 14th, 21st and 28th of the approximately 29- or 30-day lunar month as "holy days", also called "evil days" (meaning inauspicious for certain activities). On these days, officials were prohibited from various activities and common men were forbidden to "make a wish", and at least the 28th was known as a "rest day".[22]On each of them, offerings were made to a different god and goddess. Though similar, the later practice of associating days of the week with deities or planets is not due to the Babylonians.[23]
A continuous seven-day cycle that runs throughout history without reference to the phases of the moon was first practiced inJudaism, dated to the 6th century BCE at the latest.[24][25]
There are several hypotheses concerning the origin of thebiblical seven-day cycle.
Friedrich Delitzsch and others suggested that the seven-day week being approximately a quarter of alunation is the implicit astronomical origin of the seven-day week,[26] and indeed theBabylonian calendar usedintercalary days to synchronize the last week of a month with the new moon.[27] According to this theory, the Jewish week was adopted from the Babylonians while removing the moon-dependency.
George Aaron Barton speculated that the seven-day creation account of Genesis is connected to the Babylonian creation epic,Enûma Eliš, which is recorded on seven tablets.[28]
In a frequently-quoted suggestion going back to the early 20th century,[29] the HebrewSabbath is compared to the Sumeriansa-bat "mid-rest", a term for thefull moon. The Sumerian term has been reconstructed as renderedSapattum orSabattum inBabylonian, possibly present in the lost fifth tablet of theEnûma Eliš, tentatively reconstructed[according to whom?] "[Sa]bbath shalt thou then encounter, mid[month]ly".[22]
However,Niels-Erik Andreasen,Jeffrey H. Tigay, and others claim that theBiblical Sabbath is mentioned as a day of rest in some of the earliest layers of thePentateuch dated to the 9th century BCE at the latest, centuries before theBabylonian exile of Judah. They also find the resemblance between the Biblical Sabbath and the Babylonian system to be weak. Therefore, they suggest that the seven-day week may reflect an independentIsraelite tradition.[30][31][32][33] Tigay writes:
It is clear that among neighboring nations that were in position to have an influence over Israel – and in fact which did influence it in various matters – there is no precise parallel to the Israelite Sabbatical week. This leads to the conclusion that the Sabbatical week, which is as unique to Israel as the Sabbath from which it flows, is an independent Israelite creation.[32][34]
The seven-day week seems to have been adopted, at different stages, by thePersian Empire, inHellenistic astrology, and (viaGreek transmission) inGupta India andTang China.[d][citation needed]The Babylonian system was received by the Greeks in the 4th century BCE (notably viaEudoxus of Cnidus). Although some sources, such as the Encyclopædia Britannica,[8] state that the Babylonians named the days of the week after the five planets, the sun, and the moon, many scholars disagree.Eviatar Zerubavel says, "the establishment of a seven-day week based on the regular observance of the Sabbath is a distinctively Jewish contribution to civilization. The choice of the number 7 as the basis for the Jewish week might have had an Assyrian or Babylonian origin, yet it is crucial to remember that the ancient dwellers of Mesopotamia themselves did not have a seven-day week."[36] The astrological concept ofplanetary hours is an innovation of Hellenistic astrology, probably first conceived in the 2nd century BCE.[37]
The seven-day week was widely known throughout theRoman Empire by the 1st century CE,[38] along with references to the Jewish Sabbath by Roman authors such asSeneca andOvid.[39] When the seven-day week came into use in Rome during the early imperial period, it did not immediately replace the older eight-daynundinal system.[40] The nundinal system had probably fallen out of use by the time EmperorConstantine adopted the seven-day week for official use in CE 321, making theDay of the Sun (dies Solis) a legal holiday.[41]
TheZoroastrian calendar follows the Babylonian in relating the 7th, 14th, 21st, and 28th of the 29- or 30-day lunar month toAhura Mazda.[42]The forerunner of all modern Zoroastrian calendars is the system used to determine dates in thePersian Empire, adopted from the Babylonian calendar by the 4th century BCE.
Frank C. Senn in his bookChristian Liturgy: Catholic and Evangelical points to data suggesting evidence of an early continuous use of a seven-day week; referring to the Jews during theBabylonian captivity in the 6th century BCE,[25] after the destruction of theTemple of Solomon.While the seven-day week in Judaism is tied toCreation account in theBook of Genesis in theHebrew Bible, it is not clear whether the Genesis narrative predates theBabylonian captivity of the Jews in the 6th century BCE. At least since theSecond Temple period under Persian rule, Judaism relied on the seven-day cycle of recurringSabbaths.[25]
Tablets[citation needed] from the Achaemenid period indicate that thelunation of 29 or 30 days basically contained three seven-day weeks, and a final week of eight or nine days inclusive, breaking the continuous seven-day cycle.[22]The Babylonians additionally celebrated the 19th as a special "evil day", the "day of anger", because it was roughly the 49th day of the (preceding) month, completing a "week of weeks", also with sacrifices and prohibitions.[22]
Difficulties withFriedrich Delitzsch'sorigin theory connecting HebrewShabbat with the Babylonianlunar cycle[43] include reconciling the differences between an unbroken week and a lunar week, and explaining the absence of texts naming the lunar week asShabbat in any language.[44]
InJewish sources by the time of theSeptuagint, the term "Sabbath" bysynecdoche also came to refer to an entire seven-day week,[45] the interval between two weekly Sabbaths.Jesus's parable of thePharisee and the Publican describes the Pharisee as fasting "twice in the week". In the account of the women finding the tomb empty, they are described as coming there "toward the one of the sabbaths"; translations substitute "week" for "sabbaths".
The ancient Romans traditionally used the eight-daynundinum but, after theJulian calendar had come into effect in 45 BCE, the seven-day week came into increasing use. For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted byConstantine in 321 CE, the nundinal cycle had fallen out of use. The association of thedays of the week with the Sun, the Moon and the five planets visible to the naked eye dates to theRoman era (2nd century).[46][25]
The continuous seven-day cycle of the days of the week can be traced back to the reign ofAugustus; the first identifiable date cited complete withday of the week is 6 February 60 CE, identified as a "Sunday" (asviii idus Februarius dies solis "eighth day before the ides of February, day of the Sun") in a Pompeiian graffito. According to the (contemporary) Julian calendar, 6 February 60 was, however, aWednesday. This is explained by the existence of two conventions of naming days of the weeks based on theplanetary hours system: 6 February was a "Sunday" based on the sunset naming convention, and a "Wednesday" based on the sunrise naming convention.[47]
According to Islamic beliefs, the seven-day week concept started with the creation of the universe by Allah.Abu Huraira reported thatMuhammad said: Allah, the Exalted and Glorious, created the clay on Saturday and He created the mountains on Sunday and He created the trees on Monday and He created the things entailing labour on Tuesday and created light on Wednesday and He caused the animals to spread on Thursday and created Adam after 'Asr on Friday; the last creation at the last hour of the hours of Friday, i.e., between afternoon and night.[48]
The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century in theJin dynasty, while diffusions from theManichaeans are documented with the writings of the Chinese Buddhist monkYi Jing and the Ceylonese or Central Asian Buddhist monkBu Kong of the 7th century (Tang dynasty).
The Chinese variant of the planetary system was brought to Japan by the Japanese monkKūkai (9th century). Surviving diaries of the Japanese statesmanFujiwara Michinaga show the seven-day system in use inHeian Period Japan as early as 1007. In Japan, the seven-day system was kept in use for astrological purposes until its promotion to a full-fledged Western-style calendrical basis during theMeiji Period (1868–1912).
The seven-day week was known in India by the 6th century, referenced in thePañcasiddhāntikā.[citation needed] Shashi (2000) mentions theGarga Samhita, which he places in the 1st century BCE or CE, as a possible earlier reference to a seven-day week in India. He concludes "the above references furnish aterminus ad quem (viz. 1st century) Theterminus a quo cannot be stated with certainty".[49][50]
The seven-day weekly cycle has remained unbroken inChristendom, and hence inWestern history, for almost two millennia, despite changes to theCoptic,Julian, andGregorian calendars, demonstrated by the date ofEaster Sunday having been traced back through numerouscomputistic tables to an Ethiopic copy of an early Alexandrian table beginning with the Easter of 311 CE.[51][52]
A tradition of divinations arranged for the days of the week on which certain feast days occur develops in the early medieval period. There are many later variants of this, including the GermanBauern-Praktik and the versions ofErra Pater published in 16th- to 17th-century England, mocked inSamuel Butler'sHudibras. South and East Slavic versions are known askoliadniki (fromkoliada, a loan of Latincalendae), with Bulgarian copies dating from the 13th century, and Serbian versions from the 14th century.[53]
Medieval Christian traditions associated with the lucky or unlucky nature of certain days of the week survived into the modern period. This concerns primarilyFriday, associated with thecrucifixion of Jesus.Sunday, sometimes personified asSaint Anastasia, was itself an object of worship in Russia, a practice denounced in a sermon extant in copies going back to the 14th century.[54]
Sunday, in the ecclesiastical numbering system also counted as theferia prima or the first day of the week; yet, at the same time, figures as the "eighth day", and has occasionally been so called in Christian liturgy.[e]
Justin Martyr wrote: "the first day after the Sabbath, remaining the first of all the days, is called, however, the eighth, according to the number of all the days of the cycle, and [yet] remains the first."[55]
A period of eight days, usually (but not always, mainly because of Christmas Day) starting and ending on a Sunday, is called anoctave, particularly inRoman Catholic liturgy. In German, the phraseheute in acht Tagen (literally "today in eight days") can also mean one week from today (i.e. on the same weekday). The same is true of the Italian phraseoggi otto (literally "today eight"), the Frenchà huitaine, and the Spanishde hoy en ocho.
Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is often used in European and Asian countries. It is less common in the U.S. and elsewhere.
The system for numbering weeks is theISO week date system, which is included inISO 8601. This system dictates that each week begins on a Monday and is associated with the year that contains that week's Thursday.
In practice week 1 (W01 in ISO notation) of any year can be determined as follows:
If 1 January falls on a Monday, Tuesday, Wednesday or Thursday, then the week of 1 January is Week 1. Except in the case of 1 January falling on a Monday, this Week 1 includes the last day(s) of theprevious year.
If 1 January falls on a Friday, Saturday, or Sunday, then 1 January is considered to be part of the last week of theprevious year. Week 1 will begin on the first Monday after 1 January.
Examples:
Week 1 of 2015 (2015W01 in ISO notation) started on Monday, 29 December 2014 and ended on Sunday, 4 January 2015, because 1 January 2015 fell on Thursday.
Week 1 of 2021 (2021W01 in ISO notation) started on Monday, 4 January 2021 and ended on Sunday, 10 January 2021, because 1 January 2021 fell on Friday.
Dominical letter(s) plus weekdays, dates and week numbers at the beginning and end of a year
Dominical letter(s)1
Days at the start of January
Effect1,2
Days at the end of December1
1 Mon
2 Tue
3 Wed
4 Thu
5 Fri
6 Sat
7 Sun
W01-13
01 Jan week
...
31 Dec week
1 Mon4
2 Tue
3 Wed
4 Thu
5 Fri
6 Sat
7 Sun
G(F)
01
02
03
04
05
06
07
01 Jan
W01
...
W01
31 (30)
(31)
F(E)
01
02
03
04
05
06
31 Dec
W01
...
W01
30 (29)
31 (30)
(31)
E(D)
01
02
03
04
05
30 Dec
W01
...
W01 (W53)
29 (28)
30 (29)
31 (30)
(31)
D(C)
01
02
03
04
29 Dec
W01
...
W53
28 (27)
29 (28)
30 (29)
31 (30)
(31)
C(B)
01
02
03
04 Jan
W53
...
W52
27 (26)
28 (27)
29 (28)
30 (29)
31 (30)
(31)
B(A)
01
02
03 Jan
W52 (W53)
...
W52
26 (25)
27 (26)
28 (27)
29 (28)
30 (29)
31 (30)
(31)
A(G)
01
02 Jan
W52
...
W52 (W01)
25 (31)
26 (25)
27 (26)
28 (27)
29 (28)
30 (29)
31 (30)
Notes 1. Numbers and letters in parentheses, ( ), apply to March − December in leap years. 2.Underlined numbers and letters belong to previous year or next year. 3. First date of thefirst week in the year. 4. First date of thelast week in the year.
Canada, United States, Iceland, Portugal, Japan, Taiwan, Thailand, Hong Kong, Macau, Israel, Egypt, South Africa, the Philippines, and most of Latin America
Because the week starts on either Saturday, Sunday, or Monday in all these systems, the days in aworkweek, Monday through Friday, will always have the same week number within a calendar week system. Quite often, these systems will agree on the week number for each day in a workweek:
In years where 1 January is a Saturday, ISO-8601 and the Middle Eastern system will agree, being different from Western Traditional and the Broadcast Calendar which will agree.
Note that this agreement occurs only for the week number of each day in a work week, not for the day number within the week, nor the week number of the weekends.
Theepi week (epidemiological week) is used to report healthcare statistics, as with COVID-19 cases:[59]
The epidemiological week begins on Sunday and ends on Saturday. The first epidemiological week of the year ends on the first Saturday of January, provided that it falls at least four or more days into the month. Therefore, the first epidemiological week may actually begin in December of the previous year.
Thesemiconductor package date code is often a 4 digit date code YYWW where the first two digits YY are the last 2 digits of the calendar year and the last two digits WW are the two-digit week number.[60][61]
Thetire date code mandated by the US DOT is a 4 digit date code WWYY with two digits of the week number WW followed by the last two digits of the calendar year YY.[62]
The term "week" is sometimes expanded to refer to other time units comprising a few days. Such "weeks" of between four and ten days have been used historically in various places.[63] Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to thefortnight or themonth than to the seven-day week.
Calendars unrelated to the Chaldean, Hellenistic, Christian, or Jewish traditions often have time cycles between the day and the month of varying lengths, sometimes also called "weeks".
A six-day week was used in theAkan calendar andKabiye culture inWest Africa until 1981. Several cultures used a five-day week, including theJavanese calendar and the traditional cycle of market days inKorea.[citation needed] TheIgbo have a "market week" of four days. Evidence of a "three-day week" has been derived from the names of the days of the week inGuipuscoan Basque.[64]
The Aztecs and Mayas used theMesoamerican calendars. The most important of these calendars divided a ritual cycle of 260 days (known asTonalpohualli inNahuatl andTzolk'in inYucatec Maya) into 20 weeks of 13 days (known in Spanish astrecenas). They also divided the solar year into 18 periods (winal) of 20 days and five nameless days (wayebʼ), creating a 20-day month divided into four five-day weeks. The end of each five-day week was a market day.[65][66]
The BalinesePawukon is a 210-day calendar consisting of 10 different simultaneously running weeks of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 days, of which the weeks of 4, 8, and 9 days are interrupted to fit into the 210-day cycle.
TheInternational Fixed Calendar (also known as the "Eastman plan") kept a 7-day week while defining a year of 13 months with 28 days each (364 days). Every calendar date was always on the same weekday. It was the official calendar of theEastman Kodak Company for decades.[citation needed]
A 10-day week, called adécade, was used in Revolutionary France for nine and a half years from October 1793 to April 1802.[67] TheParis Commune adopted this calendar for 18 days in 1871.
TheBahá'í calendar features a 19-day period that some classify as a month and others classify as a week.[68]
Soviet calendar, 1930. Five colors of five-day work week repeat.
Soviet calendar, 1933. Rest day of six-day work week in blue.
Days of each Gregorian month in both calendars are grouped vertically into seven-day weeks.
In theSoviet Union between 1929 and 1940, most factory and enterprise workers, but not collective farm workers, used five and six day work weeks while the country as a whole continued to use the traditional seven day week.[69][70][71]
From 1929 to 1951, five national holidays were days of rest (22 January,1–2 May,7–8 November). From autumn 1929 to summer 1931, the remaining 360 days of the year were subdivided into 72 five day work weeks beginning on1 January. Workers were assigned any one of the five days as their day off, even if their spouse or friends might be assigned a different day off. Peak use of the five day work week occurred on1 October 1930 at 72% of industrial workers. From summer 1931 until26 June 1940, each Gregorian month was subdivided into five six day work weeks, more-or-less, beginning with the first day of each month. The sixth day of each six day work week was a uniform day of rest. On1 July 1935 74.2% of industrial workers were on non-continuous schedules, mostly six day work weeks, while 25.8% were still on continuous schedules, mostly five day work weeks. The Gregorian calendar with its irregular month lengths and the traditional seven day week were used in the Soviet Union during its entire existence, including 1929–1940; for example, in the masthead ofPravda, the official Communist newspaper, and in both Soviet calendars displayed here. The traditional names of the seven day week continued to be used, including "Resurrection" (Воскресенье) for Sunday and "Sabbath" (Суббота) for Saturday, despite the government'sofficialatheism.
^"ISO 8601 Data elements and interchange formats – Information interchange – Representation of dates and times" is an international standard covering the exchange of date- and time-related data.
^In pre-modern times, days were measured either from sunset to sunset, or from sunrise to sunrise so that the length of the week (and the day) would be subject to slight variations depending upon the time of year and the observer's geographical latitude.
^Copeland (1939) states as the date for Gudea "as early as 2600 BCE";[19] the modern estimate according to theshort chronology places Gudea in the 22nd century BCE. By contrast,Anthony R. Michaelis claims that "the first great empire builder, King Sargon I of Akkad ([ruled] 2335 to 2279 BCE [viz., middle chronology]), decreed a seven-day week in his empire. He lived for 56 years, established the first Semitic Dynasty, and defeated the Sumerian City-States. Thus the Akkadian language spread, it was adopted by the Babylonians, and the seven-day week was similarly inherited from him."[20] The number seven is significant in Sumerian mythology.[21]
^It was transmitted to China in the 8th century by Manichaeans, via the country ofKang (a Central Asian polity nearSamarkand).Tang-era adoption is documented in the writings of the Chinese Buddhist monkYi Jing and the Ceylonese Buddhist monkBu Kong.According to the Chinese encyclopediaCihai, there is some evidence that the system had been adopted twice, the first time already in the 4th century (Jin dynasty), based on a reference by a Jin-era astrologer, Fan Ning.TheCihai under the entry for "seven luminaries calendar" has:
method of recording days according to the seven luminaries [七曜qī yào]. China normally observes the following order: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Seven days make one week, which is repeated in a cycle. Originated in ancient Babylon (or ancient Egypt according to one theory). Used by the Romans at the time of the 1st century CE, later transmitted to other countries. This method existed in China in the 4th century. It was also transmitted to China by Manichaeans in the 8th century from the country of Kang (康) in Central Asia.[35]
^This is just a reflection of the system ofordinal numbers in the Greek and Latin languages, where today is the "first" day, tomorrow the "second" day, etc. Compare thenundinal cycle (literally "nine-days" cycle, describing aneight-day week) of the Roman calendar, or theResurrection of Jesus (after a period of less than 48 hours) being described (in texts derived from Latin) as happening on the "third day".
^sennight at worldwidewords.org (retrieved 12 January 2017)
^Richards, E. G. (2013). "Calendars". In S. E. Urban & P. K. Seidelmann, eds.Explanatory Supplement to the Astronomical Almanac, 3rd ed. (pp. 585–624). Mill Valley, Calif.: University Science Books. 2013, pp. 592, 618.This is equivalent to saying that JD0, i.e. 1 January 4713 BCE of theproleptic Julian calendar, was a Monday.
^E. G. Richards,Mapping Time, the Calendar and History, Oxford 1999. p. 269.
^Max Vasmer,Russisches etymologisches Wörterbuch, s.v.понедельник. However, the Slavic languages later introduced a secondary numbering system that names Tuesday as the "second day".
^A month consisted of three seven-day weeks and the fourth week of eight or nine days, thus breaking the seven-day cycle every month. Consequently, there is no evidence that the days of the week were given individual names in Babylonian tradition.Pinches, T.G. (2003). "Sabbath (Babylonian)". In Hastings, James (ed.).Encyclopedia of Religion and Ethics. Vol. 20. Selbie, John A., contrib. Kessinger Publishing. pp. 889–891.ISBN978-0-7661-3698-4. Retrieved17 March 2009.
^"Each account is arranged in a series of sevens, the Babylonian in seven tablets, the Hebrew in seven days. Each of them places the creation of man in the sixth division of its series." cited after Albert T. Clay,The Origin of Biblical Traditions: Hebrew Legends in Babylonia and Israel, 1923,p. 74.
^Shafer, Byron E. (1974). "Reviewed Work:The Old Testament Sabbath: A Tradition-Historical Investigation by Niels-Erik A. Andreasen".Journal of Biblical Literature.93 (2):300–301.doi:10.2307/3263102.JSTOR3263102.
^abTigay, Jeffery H. (1998). "Shavua".Mo'adei Yisra'el: Time and Holy Days in the Biblical and Second Commonwealth Periods (Heb.), ed. Jacob S. Licht:22–23.
^Hallo, William W. (1977). "New Moons and Sabbaths: A Case-Study in the Contrastive Approach".Hebrew Union College Annual.48:1–18.JSTOR23506909.
^Friedman, Allen (September 2008). "Unnatural Time: Its History and Theological Significance".The Torah U-Madda Journal.15:104–105.JSTOR40914729, Tigay's citation.{{cite journal}}: CS1 maint: postscript (link)
^Brind'Amour, Pierre (1983).Le calendrier Romain :Recherches chronologiques (in French). Editions de l'Universitá d'Ottawa. pp. 256–275.ISBN2760347028.
^Sampey, John Richard (1915)."Sabbath: Critical Theories". InOrr, James (ed.).The International Standard Bible Encyclopedia. Howard-Severance Company. p. 2630.
^ Nerone Caesare Augusto Cosso Lentulo Cossil fil. Cos. VIII idus Febr(u)Arius dies solis, luna XIIIIX nun(dinae) Cumis, V (idus Februaries) nun(dinae) Pompeis. Robert Hannah (2013). "Time in Written Spaces". In Peter Keegan; Gareth Sears; Ray Laurence (eds.).Written Space in the Latin West, 200 BCE to 300 CE. A&C Black. p. 89.
^Neugebauer, Otto (1979).Ethiopic astronomy and computus. Verl. d. Österr. Akad. d. Wiss.ISBN978-3-7001-0289-2.
^Jayne Lutwyche (22 January 2013)."Why are there seven days in a week?".Religion & Ethics. BBC.The Roman context of the spread of Christianity meant that Rome contributed a lot to the structure and calendar of the new faith
^William Francis Ryan,The Bathhouse at Midnight: An Historical Survey of Magic and Divination in Russia, Penn State Press, 1999p. 380.
^William Francis Ryan,The Bathhouse at Midnight: An Historical Survey of Magic and Divination in Russia, Penn State Press, 1999p. 383.
^OED s.v. "weekn.", entry 1.c.: "Sometimes appliedtransf. to other artificial cycles of a few days that have been employed various peoples"
^Astronomy and Basque Language,Henrike Knörr,Oxford VI and SEAC 99 "Astronomy and Cultural Diversity",La Laguna, June 1999. It referencesAlessandro Bausani, 1982,The prehistoric Basque week of three days: archaeoastronomical notes,The Bulletin of theCenter for Archaeoastronomy (Maryland), v. 2, 16–22.1.astelehena ("week-first", Monday), 2.asteartea ("week-between", Tuesday), 3.asteazkena ("week-last", Wednesday).
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