Paraskevidekatriaphobes everywhere are quaking in fear today—not over pronouncing the word that describes them, but at what their calendars currently read: Friday the Thirteenth.

In many parts of North America, Western Europe, and Australia, the day is considered an unlucky one, and superstition leads the timid to cancel doctors’ appointments, avoid airplane trips, and generally hide under the covers. But the superstition is not universal.

Suspicion of Friday the Thirteenth in the United States only started in the early 1900s, but its origin stories stretch back thousands of years. Most hold that it combines wariness of the number thirteen—an unlucky one in Roman, Norse, early Christian, and ancient Babylonian traditions—with fear of Friday, the day of the week early sources say Christ was crucified.

Friday was also the day on which most Roman crucifixions took place, and centuries later it became the customary day for public hangings in Britain and the United States.

Fear of the number thirteen is so commonplace it has its own title, triskaidekaphobia, which comes from the Greek roots for three, ten, and fear. An old Norse legend tells of a feast in Valhalla, the home of the gods, where twelve dinner guests were interrupted by the trickster god Loki. The thirteenth guest fooled the god Höðr into killing his brother Baldr with a spear tipped in poisonous mistletoe, plunging the realm into an age of mourning.

Christ’s betrayer Judas Iscariot is also said to have been the thirteenth guest at the Last Supper, while the ancient Romans held that witches’ covens met in groups of thirteen—twelve worshipers and the devil.

In Chinese culture, however, the number thirteen (shisan 十三) can actually be considered lucky. In some pronunciations it sounds like the word for “assured living” in Cantonese (shisheng 实生).

Chinese tradition is rich with similar numerical superstition. Businessmen seek out telephone numbers with an eight for its similarity to the words for “becoming rich,” while four is one of the worst numbers for bad luck since it sounds like the word for “death.” Fourteen, however, more closely resembles “whole life,” and combined with the similarity of five-twenty-one to “I love you,” it made May 21 of this year an auspicious one for many couples to get engaged.

For important events such as births and weddings, many Chinese still turn to the Chinese lunar-solar calendar. The zodiac years based on the movement of the calendar are said to be more or less fortunate—couples are trying to avoid having babies in 2015’s Year of the Sheep, for instance, based on the superstition that people born in those years are meek, prone to heartbreak, and unlucky in business.

Specific non-calendrical superstitions prevail in certain areas of China; in coastal Shandong Province, the birthplace of Confucius, fishermen do not flip over a fish on the dinner table because of its resemblance to a boat capsizing. Girls only wear white hair ornaments for attending a funeral, and men avoid wearing green hats after an old adage that it signifies a cheating wife.

It’s less consulted in modern practice than it once was, but the Chinese Almanac provides a guide to favorable and ill-starred activities for every day of the year. According to the Pocket Chinese Almanac (translated by 2014 Smithsonian Folklife Festival presenters Joanna C. Lee and Ken Smith), June 13, 2014, is a good day for rituals and making fish nets and a bad day for planting and digging wells.

These aren’t necessarily just for fisherman and farmers—“making fish nets” can mean any business overhauls (“perhaps an upgrade on your internet browser?”), while planting equates to starting a new venture or project. “Digging wells” can also refer to deep introspection—so whether you put it off until tomorrow, or ponder it today while you’re inside with the blinds drawn, take a moment to think about how and where the superstitions we cling to arise.

Meg Boeni is a media intern at the Center for Folklife and Cultural Heritage and a journalism student at Boston University. Learn more about Chinese traditions in the China: Tradition and the Art of Living program of the 2014 Folklife Festival, which opens on June 25, a good day for rituals.