What links the Ladybird, a versatile Norse goddess and her Roman counterpart, every woman in Germany and a Christmas office party ritual?

Furthermore, what has all that to do with paraskavedekatriaphobia and the reason for setting fire to your socks on the roof of 80% of the world’s skyscrapers? The answer is Friday, its mythology and the many superstitions that surround it.

In most of Northern Europe, the word for Friday comes from a couple of Norse goddesses, Freyja and Frigg, respectively the highest ranking deities of their warring pantheons, the Vanir and the Aesir. In English the name comes from Frigg, with the Anglo-Saxon spelling being Frigedæg, but in all the other teutonic languages, equivalents of Friday like Freitag in Germany are attributed to Freyja. The two goddesses are often confused, however, and some scholars of Norse mythology go so far as to believe that they are essentially the same non-existent being.

Freyja and Frigg are the rough Norse equivalents of the Roman goddess, Venus, who gives her name to many Romance language variants of Friday – Vendredi is the French version, for example. Indian languages follow suit with the name Shukravar, derived from the Sanskrit word for Venus, Shukra.

Freyja is not only an equivalent of Venus, but also of the Madonna. The connection is apparent in a number of plants that bore her name in Scandinavia but which rapidly switched their dedication to the Virgin Mary as part of the process of Christianisation. One of the clearest examples, however, can be found in the name of the humble Ladybird, itself a contraction of ‘Our Lady’s bird’, but which was once known as Marienvoglein in Middle German, while the West Frisians prefer ‘ingeltsje’ which translates as the devout, though very pretty, ‘little angel’. Before the impact of the early Christian missionaries, who sought to wipe out all traces of indigenous pagan practices, the Ladybird was known as Freyjuhaena. The parallels between Freyja and Mary must have been obvious to the Christians, who superimposed the Madonna onto the Norse goddess of love and fertility. In German, Freyja also gave her name to the Old Norse word for ‘lady’ – with fru making it into modern Scandinavian and frau in modern German. In turn and in her own way, Freyja has managed to infiltrate the Christian tradition in a typically bawdy, Viking manner. Being the goddess of fertility, she was linked with mistletoe which, despite still being considered by the Anglican church as a pagan plant, has inveigled its way into Christmas in English-speaking cultures the world over.

Why does the tax year start on the 6 April?

Surprisingly, the answer has nothing at all to do with accountancy and everything to do with sex or, more appropriately, conception. But that’s not the whole story – the insolence of the authorities responsible for taxation in the eighteenth century also plays a part, as does a certain sixteenth century pope.

Until England’s adoption of the Gregorian calendar in 1752, the Feast of the Annunciation, or ‘Lady Day’ was the start of the civil new year, being the first of the four quarter days that marked our annual journey around the sun. Lady Day marks the conception of Jesus. At the same time as the new style calendar was adopted, the administrative new year was also changed to January 1.

Under the old style Julian calendar, the Annunciation was celebrated on March 25 – exactly nine months before Christmas – and this continued under the Gregorian calendar, first introduced by Pope Gregory XIII on Friday October 15, 1582, despite now occurring ten days earlier all of a sudden. The forces of English accountancy were less flexible and when the Calendar (New Style) Act was passed in 1750 to implement the Gregorian calendar, the tax collection authorities and landlords of the day were faced with the threat of losing 11 days of revenue and provision 6 (Times of Payment of Rents, Annuities, &c.) was written in to add the missing days to the end of the 1752-3 tax year, so that the next financial year started on April 5. In a similar fashion, when the first skipped leap year came around in 1800 (under the Gregorian calendar, years divisible by 100 do not have an extra day unless they are also divisible by 400) the start of the tax year was extended a further day to April 6 and has remained there ever since.

Which English King apparently travelled back in time?

Different nations adopted the New Style calendar at different times, which led to plenty of confusion in affairs between states. Possibly the worst instance of jet-lag ever occurred when William III of England set sail from the Netherlands on November 11 (Gregorian) 1688 and arrived at Brixham in Devon on November 5 (Julian).

When Alaska was sold by Russia to the United States of America in 1867, the old Russian territory was still operating on the Julian calendar, in common with the rest of Russia. Not content with introducing the Gregorian year, which would have resulted in lopping 12 days from October, the US also moved the International Date Line to run west of the new state instead of east , which cut back the deficit to 11 days. This bold move was not without its complications, however and Friday, October 6, 1867 was followed the next day by another Friday on October 18. Russia did not officially let go of the Julian calendar until 1918 – its October Revolution of 1917 took place in November, as far as almost all the rest of the world was concerned. The Russian Army famously arrived late to their rendezvous with the Austrians at the Battle of Austerlitz because the Austrian Army were 12 days ahead of them which was probably a contributing factor in Napolean’s victory.

Why did the new millenium not start on January 1, 2001?

Revenge is at hand for everyone who had to suffer an attack of righteous pedantry for daring to step in line and get hopelessly drunk on New Year’s Eve, 1999. Contrary to what tiresome people would have you believe, New Year’s Day, 2001 was not the first day of the third millenium at all. Though now hopelessly lost in the confusion caused by the adoption of the Gregorian calendar and re-alignment of the new year, the AD calendar didn’t even start on January 1 at all, but with the conception of Jesus at the Annunciation. Lady Day on Friday, March 25, 1 A.D. Adding 730487 days – the sum of 2000 years – to that date brings us to March 25, 2001, but it’s not even that simple. Though a huge improvement over the Julian calendar, the Pope’s numbers were just not right at all – we now know that there is a tiny error in the length of the year in the assumptions which underpin the Gregorian calendar – an error which leads me to assert that the third millenium actually started just after 9.33 a.m. on Thursday March 22, 2001, which, I think you’ll agree, is just the kind of nonsense you would expect from scientific empirical measurement. The old Pope would have been proud.

Why is having an unlucky day statistically likely?

An interesting by-product of the Gregorian calendar is that it does not treat all days and dates equally. You might think that, given a long enough time frame, the likelihood of the thirteenth of the month falling on a Friday would work out to be exactly 1 in 7. Unfortunately, Friday is the most likely day on which the 13th will occur and someone actually sat down and worked out that there will be 688 Friday 13s in any 400 year cycle – the length of time that the Gregorian calendar takes to repeat itself exactly. The least likely day is Saturday which would score 684 on the same scale. So, it’s marginal, but if you are of a paraskavedekatriaphobic nature, you will probably nod your head in agreement when I tell you that the calendar is ever so slightly rigged against you.