seven day week has been used for millennia by the Christian,
Jewish, Islamic, and Chinese calendars, yet its origins are
What Is the
Origin of the 7-Day Week?
the history of the 7-day week is a very complicated matter.
Authorities have very different opinions about the history
of the week, and they frequently present their speculations
as if they were indisputable facts. The only thing we seem
to know for certain about the origin of the 7-day week is
that we know nothing for certain.
The common explanation is that the seven-day week was established
as imperial calendar in the late Roman empire and furthered
by the Christian church for historical reasons. The British
Empire used the seven-day week and spread it worldwide. Today
the seven-day week is enforced by global business and media
schedules, especially television and banking.The first pages
of the Bible explain how God created the world in six days
and rested on the seventh. This seventh day became the Jewish
day of rest, the sabbath, Saturday.Extra-biblical locations
sometimes mentioned as the birthplace of the 7-day week include:
Babylon, Persia, and several others. The week was known in
Rome before the advent of Christianity.
There are practical geometrical theories as well. For example,
if you wrap a rubber band around 7 soda cans (or any other
convenient circular objects). You get a perfect hexagon with
the 7th can in the middle. It is the only stable configuration
of wrapping more than 3 circular objects. Four, 5, and 6 objects
will slip from one configuration to another. Ancients wrapping
tent poles, small logs for firewood, or other ciruclar objects
might have come upon this number and attach a mystical significance
One viable theory correlates the seven day week to the seven
(astrological) "planets" known to the ancients:
Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. The
number seven does not seem an obvious choice to match lunar
or solar periods, however. A solar year could be more evenly
divided into weeks of 5 days, and the moon phases five-day
and six-day weeks make a better short term fit (6 times 5
is 30) to the lunar (synodic) month (of about 29.53 days)
than the current week (4 times 7 is 28). The seven-day week
may have been chosen because its length approximates one moon
phase (one quarter = 29.53 / 4 = 7.3825).
Do the Names of the Days of the Week Mean?
An answer to
this question is necessarily closely linked to the language
in question. Whereas most languages use the same names for
the months (with a few Slavonic languages as notable exceptions),
there is great variety in names that various languages use
for the days of the week. A few examples will be given here.
Except for the sabbath, Jews
simply number their week days.
A related method is partially
used in Portuguese and Russian:
of Russian name
languages connect each day of the week with one of the seven
"planets" of the ancient times: Sun, Moon, Mercury,
Venus, Mars, Jupiter, and Saturn. French, for example, uses:
The link with
the sun has been broken in French, but Sunday was called dies
solis (day of the sun) in Latin.
It is interesting to note that also some Asiatic languages
(for example, Hindi, Japanese, and Korean) have a similar
relationship between the week days and the planets.English
has retained the original planets in the names for Saturday,
Sunday, and Monday. For the four other days, however, the
names of Anglo-Saxon or Nordic gods have replaced the Roman
gods that gave name to the planets. Thus, Tuesday is named
after Tiw, Wednesday is named after Woden, Thursday is named
after Thor, and Friday is named after Freya.
connotations of the days of the week from a sampling of cultures
and time periods.
is the System behind the Planetary Day Names?
As we saw
in the previous section, the planets have given the week days
their names following this order:
Mercury, Jupiter, Venus, Saturn, Sun
Why this particular
goes as follows: If you order the "planets" according
to either their presumed distance from Earth (assuming the
Earth to be the center of the universe) or their period of
revolution around the Earth, you arrive at this order: Moon,
Mercury, Venus, Sun, Mars, Jupiter, Saturn
(in reverse order) these planets to the hours of the day:
3=Mars, 4=Sun, 5=Venus, 6=Mercury, 7=Moon, 8=Saturn, 9=Jupiter,
etc., 23=Jupiter, 24=Mars
Then next day
will then continue where the old day left off:
etc., 23=Venus, 24=Mercury
And the next
day will go
If you look
at the planet assigned to the first hour of each day, you
will note that the planets come in this order:
Moon, Mars, Mercury, Jupiter, Venus
This is exactly
the order of the associated week days.
the 7-Day Week Cycle Ever Been Interrupted?
no record of the 7-day week cycle ever having been broken.
Calendar changes and reform have never interrupted the 7-day
cycles. It very likely that the week cycles have run uninterrupted
at least since the days of Moses (c. 1400 B.C.E.), possibly
claim that the ancient Jews used a calendar in which an extra
Sabbath was occasionally introduced. But this is probably
Day is the Day of Rest?
Jews, the Sabbath (Saturday) is the day of rest and worship.
On this day God rested after creating the world.
have made Sunday their day of rest and worship, because Jesus
rose from the dead on a Sunday.
Friday as their day of rest and worship. The Qur'an calls
Friday a holy day, the "king of days."
Is the First Day of the Week?
clearly makes the Sabbath the last day of the week, but does
not share how that corresponds to our 7 day week. Yet through
extra-biblical sources it is possible to determine that the
Sabbath at the time of Christ corresponds to our current 'Saturday.'
Therefore it is common Jewish and Christian practice to regard
Sunday as the first day of the week (as is also evident from
the Portuguese names for the week days). However, the fact
that, for example, Russian uses the name "second"
for Tuesday, indicates that some nations regard Monday as
the first day.
standard ISO-8601 the International Organization for Standardization
(ISO) has decreed that Monday shall be the first day of the
Is the Week Number?
standard ISO-8601 assigns a number to each week of the year.
A week that lies partly in one year and partly in another
is assigned a number in the year in which most of its days
lie. This means that
Week 1 of any
year is the week that contains 4 January,
Week 1 of any year is the week that contains the first Thursday
have 52 weeks, but years that start on a Thursday and leap
years that start on a Wednesday have 53 weeks.
can I calculate the week number?
know the date, how do you calculate the corresponding week
number (as defined in ISO-8601)?
formulas in the section on the Christian calendar, calculate
the Julian Day Number, J.
the following calculations (in which the divisions are
integer divisions in which the remainder is discarded):
d4 = (J+31741
- (J mod 7)) mod 146097 mod 36524 mod 1461
L = d4/1460
d1 = ((d4-L) mod 365) + L
WeekNumber = d1/7+1
Weeks of Different Lengths Exist?
define a "week" as a 7-day period, obviously the
answer is no. But if you define a "week" as a named
interval that is greater than a day and smaller than a month,
the answer is yes.
Egyptians used a 10-day "week", as did the French
Revolutionary calendar (see French calendar).
The Maya calendar
uses a 13 and a 20-day "week" (see Mayan calendar).
Union used both a 5-day and a 6-day week. In 1929-30 the USSR
gradually introduced a 5-day week. Every worker had one day
off every week, but there was no fixed day of rest. On 1 September 1931
this was replaced by a 6-day week with a fixed day of rest,
falling on the 6th, 12th, 18th, 24th, and 30th day of each
month (1 March was used instead of the 30th day of February,
and the last day of months with 31 days was considered an
extra working day outside the normal 6-day week cycle). A
return to the normal 7-day week was decreed on 26 June 1940.
used week of nine days before adopting Cristianity.
day was a certain date?
the day on which a particular date falls, the following algorithm
may be used (the divisions are integer divisions, in which
remainders are discarded). In July 4, 1950, date=4, month=7,
year=1950. Note that "mod" means the remainder when
doing integer division, e.g., 20 mod 7 = 6. That is, 20 divided
by 7 is 2 and 6/7th (where xsi is the remainder).
= [(14 - month) / 12]
= year - a
= month + 12 a - 2
= (5 + date + y + y/4 + [31 m /
12]) mod 7
= (date + y + y/4 - [y / 100] +
[y / 400] + [31 m/ 12]) mod 7
Where day 0
is Sunday, day 1 is Monday, etc.
The week of seven days was
adopted in Rome somewhere about 400 AD, and spread into Europe,
but had been recognized as a period of time long before that
in the east. It was probably chosen to give one day each to
each of the seven planets known in antiquity. In the southern
countries of Europe, the days of the week were named after
the gods of the Greeks and Romans. In the English language,
as well as in the languages of some of the countries of northern
Europe, the gods of the north have given their names to the
The Ashanti and some other
peoples of West Africa gave a child a special name according
to the day of the week on which he was born. The habit was
brought to the American South and Caribbean through slavery,
where names such as Quashee (Sunday), Cudjo (Monday) and Cufee
(Friday) were common.
is fair of face,
Tuesday's child is full of grace,
Wednesday's child is full of woe,
Thursday's child has far to go,
Friday's child is loving and giving,
Saturday's child works hard for a living,
But the child that works hard on the Sabbath Day,
is blithe and bonny, good and gay
Monday is the second day of the week, day of moon goddess,
Selene, Luna and Mani.
Derived from Lunae Dies, day of the moon, the name reflects
the ancient observance of feast days dedicated to moon goddess
The metal silver, dedicated to the moon, is associated with
Tuesday is the third day of the week. In the Roman calendar
the corresponding day was dies Martis, the day of Mars, associated
with Ares. Tiw's day is derived from Tyr or Tir, the god of
honorable war, the wrestler and the son of Odin and, or Woden,
the Norse god of war and Frigga, the earth mother. His emblem
is the sword, and in olden days the people paid him great
homage. Tuesday was named in his honor.
The metal iron,
dedicated to Mars and interpreted as his spear and shield,
is an attribute of Tuesday
Wednesday, the fourth day of the week, corresponds to the
Roman Dies Mercurii. The name derives from the Scandinavian
Woden (Odin), chief god of Norse mythology, who was often
called the All Father.
Quicksilver, a liquid mercury that contains amounts of the
platinum group metals, has been interpreted as the caduceus
of the Greek Hermes (Mercury in Roman myth), and is therefore
an attribute of Wednesday
Thursday is the fifth day of the week. It derives its name
from the Middle English Thoresday, or Thursdaye, corresponding
to the Roman dies Jovis.
Thor, the god of strength and thunder, defender and help in
war, son of Odin, is the counterpart of Jupiter or Jove. Thor
is one of the twelve great gods of northern mythology. He
is the only god who cannot cross from earth to heaven upon
the rainbow, for he is so heavy and powerful that the gods
fear it will break under his weight. It was said that whenever
Thor threw his hammer, the noise of thunder is heard through
the heavens. Thursday was sacred to Thor.
The metal tin
is associated with the thunderbolt of Jupiter (Zeus in Greek
myth) and is an attribute of Thursday.
I am the
Here in my Northland,
My fastness and fortress,
Reign I forever!
--Henry Wadsworth Longfellow
Friday is the
sixth day of the week. The name is derived from the Germanic Frigga the name of the Norse god Odin's wife. Frigga
is considered to be the mother of all, and the goddess who
presides over marriage. The name means loving or beloved.
The corresponding Latin name is Dies Veneris, a day dedicated
to Venus, the goddess of love.
The metal copper, dedicated to Venus, is associated with Friday.
Saturday is the seventh day of the week, corresponding to
the Roman dies Saturni, or day of Saturn, the Roman
god of agriculture.
Saturday is also represented by Loki, the Norse god of tricks
The metal lead
is associated with the scythe of Saturn, and is therefore
an attribute of Saturday.
Sunday is the first day of the week.
times to the close of the fifth century of the Christian era,
the worship of the sun was dominant.
the sun god, Ra, Helios, Apollo, Ogmios, Mithrias, the sun
The metal gold,
as dedicated in the symbols of alchemy, is associated with
the sun god and Sunday.
In the year
321, Constantine the Great ruled that the first day of the
week, 'the venerable day of the sun', should be a day of rest.
The sun's old association with the first day is responsible
for the fact that the Lord's Day of Christianity bears the
pagan name of Sunday.
The origins of
the names of the days
of the days are in some cases derived from Teutonic deities
or, such as in Romance languages, from Roman deities. The
early Romans, around the first century, used Saturday as the
first day of the week. As the worshipping of the Sun increased,
the Sun's day (Sunday) advanced from position of the second
day to the first day of the week (and saturday became the