If you happen to be a friggatriskaidekaphobe, then for you Murphy's Law becomes a force majeure today. You are convinced, as Hamlet puts it, that "when sorrows come, they come not as single spies, but in battalions".
Or as the poet Edward Young perceived the situation:
"Woes cluster; rare are solitary woes;
They love a train, they tread each other's heels."
This is because you have a morbid fear of Friday 13th.
It is an important principle of the philosophy of any ardent friggatriskaidekaphobe that misfortune is cumulative. The inauspicious reputation of Friday the 13th, therefore, stems from the bad luck individually associated with both Friday and the number 13. Today's coincidence is double trouble.
In the Christian tradition, Friday is associated with the Crucifixion and, therefore, viewed with suspicion as a day of ill omen. Moreover, many undesirable or ill-fated biblical events are said to have taken place on that day: Eve allegedly gave the apple to Adam on a Friday morning and that very afternoon they were expelled from Paradise.
Moreover, Noah's flood began on Friday, and it was also on that day that the Temple of Solomon in Jerusalem was destroyed.
Thirteen has an equally unlucky aura and to understand this one has to know the history of the number 12.
Twelve was seen as the most "complete" number. There were, after all, 12 months of the year, 12 gods of Olympus, 12 signs of the zodiac and 12 apostles of Jesus. But 13 exists just one digit beyond and was symbolic of the first departure from completeness, or the initial step towards evil.
Judas Iscariot, for example, was the "13th" apostle, and the 13th tribe of Israel was the only tribe left without a tract of land.
Norse mythology associates 13 with the death of the god Bandur. Bandur, the god of light - and, coincidentally, the son of the goddess Frigg, after whom Friday and friggatriskaidekaphobes are named - was unfortunate enough to be at a banquet in Valhalla with 11 others when his old enemy, Loki, god of strife, gained entry through a subterfuge. Once in, this 13th guest arranged the death of Bandur.
The combination of Friday and 13 is no less common on the calendar that that of any other day and date - but the unlucky day is rare enough.
All years have at least one Friday 13th, most years have two, and if, like this year, New Year's Day in a non-leap year falls upon a Thursday, there are three. We will have the others next month and in November.