Most societies across the world have some form of week, though its number of days can vary from three to 16. The Inca used eight-day weeks whereas the Maya, for whom time was a deity, considered a 260-day cycle the most important time unit in the calendar, representing the nine-moons-time between conception and childbirth. For Native North Americans (such as Hopi, Navajo), where time was embodied in nature's rhythms and processes, ceremonies were not governed by clock or calendar but by seasons.

In ancient Egypt the Sun god Re (Ra) was the lord of time, setting its measures when he sails in his barge over the upper and lower firmament. Each hour he assumes the shape of a different animal god, thus acquiring changing qualities and becoming manifest in an endless circular procession. Around the third millennium BC, the Egyptians, having invented picture writing or hieroglyphs, adopted a civil calendar, derived from the lunar calendar. The civil year¹ had 360 + 5 days and started with the seasonal re-appearance of the Dog Star, Sirius, in the eastern sky followed by the annual flood of the River Nile. They used this combination of events to fix their calendar (comprising ten-day weeks) but did not allow for the extra quarter of a day and subsequently their calendar drifted into error².

Aboriginal Australians provide an extraordinary model of time, being subtle, ambiguous and diffuse. The Dreamtime or Alcheringa is a sacred time, a Great Time, qualitatively different from ordinary or chronological time. Whereas the Western mind sees past or present or future, the Aboriginal sees them as merging, Dreamtime as always immanent in the land; the wallaby at the waterhole now, this Wednesday or last Wednesday or next Wednesday (ie, always existing at the totemic waterhole in Dreamtime Wednesday).

The cycles of the Moon, and above all the course of the Sun, gave humankind a measure of time³. Sundials were found in Egypt from the 13th Century BC onwards, but probably the Babylonians knew it first. They began to observe the motions of the stars and gather arithmetical information about their movements. They began to realise the existence of a lawful order in this procession of gods or archetypes over the sky; this order they expressed by numbers. Thus the Babylonians translated 'time' into numbered measurements, designed a seven-day week, which was later adopted by Judeo-Christianity to become the Western model of time.

But why seven days of the week? Firstly, the week is an artificial division of time, having no correlation with any astronomical or natural phenomena except insofar as it is a closed system. We can deduce, therefore, that the number seven had a special or archetypal significance to ancient civilisations, that it was a sacred number or at least a derivative of one. In watching and worshipping the stars the Babylonians, like the ancient Egyptians, attempted to faithfully recreate on earth the celestial order of the macrocosm, the guiding injunction being 'as above, so below.' There can be little doubt that the seven-day week is a legacy of the ordering process of patriarchal cultures of antiquity and mythologies surrounding the 12-month solar and 28-day lunar cycles, linked to the traditional seven planets, the seven stars, the Great Bear  constellation that is the centre of the World Tree, the navel of the world...

Bleakley⁴ supports the notion of the menstrual cycle as a key structural force of human life. He explains that the four-fold expression of the seven-day creation myth in the book of Genesis is the traditional number of the menstrual cycle, the 28-day lunar approximation. Here is the fountain of Renewal, the navel of the World, a mandala radiating in four directions, representing the four quarters of the moon cycle and the menstrual rhythm.

The Babylonians named each day of the week after one of the five planetary bodies known to them, and after the Sun and the Moon; a custom later adopted by the Romans.

It was Emperor Constantine in 321AD who, adhering to the concept of linear time, established the 7 day week in the Roman Calendar and designated Sunday (Sabbath) as the first day of the week⁵.

Subsequent days bore the names:

• Moon's-day
• Mars's-day
• Mercury's-day
• Jupiter's-day
• Venus's-day, and,
• Saturn's-day

The days assigned by the Romans to the Sun, Moon and Saturn were retained for the corresponding days of the week in English (i.e. Sunday, Monday and Saturday respectively).

The other weekday names in English are derived from Anglo-Saxon words for the Gods of Teutonic mythology. Tuesday comes from Tiv, or Tiw, the anglo-saxon name for Tyr⁶, the Norse god of war (equivalent of the Germanic Mars or Ares).

Tyr was one of the sons of Odin, or Woden, the supreme deity after whom Wednesday (Woden's-day) was named. Similarly, Thursday originates from Thor's-day, named in honour of Thor, the god of thunder. Friday was derived from Frigg's-day. Frigg (also called Friia), the wife of Odin, represents love and beauty in Norse mythology, ergo promoter of marriage and fertility.

Below is a table of the etymology of days with names and attributes of corresponding Gods and Goddesses