01(08): Days of the week

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We deal with them all the time. ‘Arrghh, I hate Mondays; Monday blues!’ is something that is commonly heard. ‘Let’s have lunch on Saturday’. ‘I have dinner with my family on Sunday’. ‘I have a dental appointment on Wednesday’. These sentences are not unusual, and we do not give the days’ names a second thought even as we cite them throughout our lives.

As with basically anything fancy, it can probably be traced back to the Greeks and Romans. The names of the days of the week are derived from the names of the then-contemporary deities; the planets were, and still are, associated with deities. What the Greeks did with the days of the week was highly influential. After them, the Romans adopted it. Soon enough, the whole world adopted a seven-day week. However, if we dig deeper, we learn that it didn’t begin with the Greeks. It goes all the way back to the ancient Babylonians.

Before the rise of the Greeks, it was the ancient Babylonians who were living in the cradle of civilisation. They were formidable astronomers and they devised their calendars to predict the movements of heavenly bodies. Unlike the year which closely corresponds to the period of Earth’s revolution around the Sun, and the month, which closely corresponds to the Moon’s revolution around the Earth, the week has no analogue. The week came to have seven days because the Mesopotamian astrologers designated one day for each of the seven most prominent objects in the sky: the Sun, the Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Do you see something familiar with the way I listed the seven celestial bodies?

After the ancient Babylonians, in came the Greeks with their extensive mythology, which had been around since 1800 BC. As we said earlier, the planets are associated with deities in Greek.

Between the 1st and 3rd centuries, the Roman Empire gradually replaced the eight-day Roman nundinal cycle (the nundinal cycle, market week, or 8-day week was the cycle of days preceding and including each nundinae) with the seven-day week. Our earliest evidence for this new system is a Pompeiian graffito referring to 6 February AD 60 as dies solis (literally Latin for ‘day of the Sun’). The Latin word for the Sun is ‘sol’. You see the suffix ‘-is’ as in ‘solis’ because the genitive case is being used (i.e. indicating possession; ‘of the Sun’). The word ‘sol’ is where we get words such as ‘solar’.

Another early witness is a reference to a lost treatise by Plutarch (a Greco-Roman biographer), written in about AD 100, which addressed the question of ‘Why are the days named after the planets reckoned in a different order from the actual order?’ I bet this must have been the question in your mind as I told you about the celestial bodies four paragraphs earlier. Well, you’re nearly two millennia late.

Anyway, let’s not get distracted. The days were named after the planets of Hellenistic astrology, in the order Sun, Moon, Mars (Ares), Mercury (Hermes), Jupiter (Zeus), Venus (Aphrodite) and Saturn (Chronos). Yes, that’s the same way the fashion brand is spelt – Hermes. The seven-day week spread throughout the Roman Empire during Late Antiquity. By the fourth century, it was used throughout the empire, and it had also reached India and China.

Let us dissect each day. Before we move on, we should note that people back then had the practice where gods across different mythologies would be one and the same. For example, the Roman goddess of the Moon (Luna) would be taken to be the same entity as the Greek goddess of the Moon (Selene). The Germanic people adapted the system introduced by the Romans by substituting the Germanic deities for the Roman ones (with the exception of Saturday).


The Greek word for Sun ‘helios’ is where we get the word ‘heliocentric’ (cf the historical dispute between the geocentric and heliocentric model for the solar system; the phrase ‘solar system’ gives a hint as to what the correct model is; haha).

In OE (Old English) Sunnandæg, meaning “sun’s day”. That strange symbol in that word is called a digraph (a combination of two letters representing one sound). This is a translation of the Latin phrase dies Solis. English. Like most of the Germanic languages, it preserves the day’s association with the Sun. Many other European languages, including all of the Romance languages, have changed its name to the equivalent of “the Lord’s day” (based on Ecclesiastical Latin dies Dominica). In both West Germanic and North Germanic mythology, the Sun is personified as Sunna/Sól. Hence, we see that in Romance languages such as French and Italian, Sunday has become dimanche and domenica respectively. ‘Domenica’ is a Christian reference to Jesus.

In Russian,the word for Sunday is voskresen’je (воскресенье), and it means ‘resurrection’ (cf Christ was crucified on a Friday, which Good Friday commemorates, and resurrected on a Sunday, which Easter Sunday commemorates).

This change to a reference to Christ probably never happened in English because of a division in language between different classes after the Norman invasion of 1066. While the official Norman-French language in use among the lordly elite switched effortlessly into official Latin and used the ‘Lord’s Day’, Anglo-Saxon remained the vernacular of ordinary folk.

It should be noted that Emperor Constantine the Great had converted Rome to Christianity and standardised the seven-day week across the Empire. According to Dr Matthew Nicholls, senior lecturer in Classics at the University of Reading: ‘The Roman context of the spread of Christianity meant that Rome contributed a lot to the structure and calendar of the new faith.’ Rome may initially have acquired the seven-day week from the mystical beliefs of Babylonian astrologers, but it was the biblical story of creation, God’s creation of the heaven and the earth, and resting on the seventh day that would have led the first Christian emperor of Rome to ensure that the seven-day week endures to this day.


Monday is a shortened form of ‘Day of the Moon’. It shouldn’t be too difficult to see how ‘Luna’ relates to Monday. It is from the Roman goddess that we get words such as ‘lunar’, ‘lunatic’ and ‘lunacy’ – a condition which has been associated with the lunar cycle. In Roman mythology, Diana, the twin of Apollo the Sun-god, is the goddess of the moon, the hunt, and child birth. Diana is considered to be the same as Luna and Selene.


In Greek and Latin, we see that Tuesday is the ‘Day of Ares’ and the ‘Day of Mars’ respectively. As I said earlier, they were considered to be the same entity. Mars is known as the Roman god of war. It is where we get words such as ‘martial’ as in ‘court-martial’ and ‘martial arts’. The English word Tuesday is also derived from OE and from the Norse god of war Tiw (or Týr). Consider the historical development of Tuesday (ME tewesday, OE tiwesdaeg, OHG ziestac). By the way, ME and OHG refer to Middle English and Old High German respectively.


The following chunk regarding Wednesday is a direct quote from reference [1]:

Wednesday comes from ‘Woden’, the Old German and English name for the Norse god Odin. Odin is father and ruler of the gods and mortals, often called ‘the all father’. He is also the god of war, learning, poetry and the dead. He had only one eye, having traded his second for a drink from the Well of Wisdom. Odin was considered to be one and the same with Mercury. He is the ruler of Asgard, the home of the gods, and is able to shift and change into different forms. In contrast, Mercury, the Roman god for whom dies Mercurii is named, is a messenger god. While Woden survives in English, he disappeared from the days of the week in German. This dates from the time Christianity was displacing pagan beliefs in the centuries following the collapse of the Roman Empire. “In Germany they found themselves the heirs to classical Rome as the Carolingian leaders of the Holy Roman Empire, so along with Christianisation went a willingness to embrace all that that new title meant” explains archaeologist Iain Sodden. In German, Wednesday or Woden’s day was replaced with Mittwoch or ‘mid-week’.


Thor, Jupiter, and Zeus were all gods of thunder. Thursday comes from ‘Thor’s Day’. Nothing much here.


Friday is linked with Venus. This day is unique because it is the only day named after a woman. Friday comes from OE/ME Frigedaeg or ‘Frigga’s day’. Frigg was the wife of Odin, and the goddess of love and beauty. Venus was the goddess of sex, love and fertility. She is also associated with marriage and fertility. Venus can outshine any of the other planets, and was the Roman goddess of love, beauty, sex, fertility, prosperity and victory. Venus was closely associated with the Greek goddess Aphrodite.


This is an easy one. Saturday (cf OE Saternesdaeg) comes from ‘Day of Saturn’. This is in my opinion, the most interesting day. Saturday is the only day in English which is directly named after a Roman god. Its equivalent in Greek mythology is Chronos/Kronos, the ruler of the titans and the god of time. It is from the Greek word ‘chronos/kronos’ that we get words such as ‘chronometer’, ‘chronological’, ‘chronograph’, ‘synchronise’. Isn’t language fascinating? Saturn is the father of Jupiter, the chief Roman God. The following paragraph is a direct quote from reference [1]:

The association of Saturday with a Roman god in English helps date when the seven-day week came to Britain. According to Prof Mckinnell,, it suggests that the names of the days “may have arrived in the UK along with Latin learning – with or after the conversion to Christianity, between AD 597 and AD 685.” In the Romance languages of southern Europe which are largely derived from Latin, the word for Saturday was changed to mirror Church Latin. For example the Spanish word sábado comes from Sabbath.

The word ‘Sabbath’ is where we get words such as ‘sabbatical’. The Sabbath is observed by adherents of Judaism and Seventh-day Adventists on Saturday as a day of rest and worship.

There are more interesting things that we could discuss:
1) Plutarch’s question: ‘Why are the days named after the planets reckoned in a different order from the actual order?’
2) Why modern Mandarin only has numbered days (with the exception of Sunday 星期日)?
3) Should Sunday or Monday, or even Saturday be the start of the week?

However, this blog post would be too long. In fact, as it is, this is my longest blog post yet. Thank you for reading!

Yours faithfully,
Nicholas Loh
1 February 2019

References and Further Reading
1. http://www.bbc.co.uk/religion/0/20394641
2. https://www.quora.com/What-is-a-seven-day-week-based-on
3. http://www.calendar-origins.com/day-name-origins.html
4. https://en.wikipedia.org/wiki/Names_of_the_days_of_the_week#Days_named_after_planets
5. https://en.wikipedia.org/wiki/Hellenistic_astrology
6. https://en.wikipedia.org/wiki/Greek_mythology

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