Hollywood, MD—Not only are we in the spookiest month, but today marks the spookiest day. Friday the 13th may send images of a machete wielding, hockey mask wearing serial killer to your mind (or even his mother), you may also think of typical unlucky tropes such as black cats or walking under a ladder. But what is the origin of this taboo day—and should we all be wary? Does something wicked this way come?

No one is truly certain of the exact origins regarding the negative connotation for Friday the 13th. However, there are a few theories. The number 13 and Friday separately had their fair share of hate prior to their conjoined dislike. The number 13 is sometimes called “the devil’s dozen,” and many hotels around the country don’t have a thirteenth floor, the numbers will skip to fourteen instead. Some apartment complexes and housing developments also forego usage of this unfortunate number. For ancient Egyptians, 13 symbolized death, as they believed that life unfolded in 12 stages—the thirteenth stage being the afterlife. In Norse mythology, the thirteenth god was Loki, the deity of evil and mischief.

The misfortune of Fridays date back to Biblical tales. Supposedly, Eve gave Adam the forbidden fruit on a Friday, which led to them having to leave the Garden of Eden. Per theorists, the Great Flood also began on a Friday, as well as the destruction of the Temple of Solomon. Jesus was also crucified on a Friday, a day which those celebrate Easter now refer to as “Good Friday.” From a secular standpoint, Friday was execution day in ancient Rome.

So with both holding historically calamitous backgrounds, what made us combine these two into the ever unlucky Friday the 13th? One theory, while its host dates back to 1307, was derived by Dan Brown in his novel The Da Vinci Code. Brown cites in his book an incident that occurred on a Friday the 13th in 1307 involving the Knights Templar, a medieval religious organization. French King Philip IV had some of the knights arrested on this day and accused them of heresy. After this, Pope Clement V disbanded the group due to the uproar.

Another religious affiliation with Friday the 13th involves Jesus’ crucifixion. As mentioned previously, Jesus was crucified on a Friday. Prior to this, Jesus and his 12 apostles partook in the Last Supper. One of Jesus’ apostles, Judas, was supposedly the 13th person to arrive to the dinner. The reason this is significant is because Judas was the one to betray Jesus, selling out his location to the chief priests for 30 pieces of silver, leading to Jesus’ crucifixion. Thus, the correlation between Friday and 13.

These are two of the more popular theories for the origin, however, the idea of Friday the 13th being an unlucky day is still a fairly new concept. In the 1898 edition of Cobham Brewer’s Dictionary of Phrase and Fable, there is no mention of Friday the 13th, however both Friday and the number 13 are listed individually as being unlucky. The first well-known documented appearance of Friday the 13th in conjoined hapless union is in Thomas W. Lawson’s 1907 novel Friday, the Thirteenth. Lawson’s novel centered around a businessman who attempted to take down Wall Street on a Friday the 13th. The book sold quite well, and created a correlation between bad luck and a bad stock market.

Is Friday the 13th actually unlucky? It all boils down to what you believe. There are several spooky events that have occurred throughout history on Friday the 13th, and airlines usually sell plane tickets cheaper on Friday the 13th as well. Could it just be a coincidence? According to phobia specialist Dr. Donald Dossey, this is the most popular superstition in the United States, with around 21 million people stating they believe in it. Will you be avoiding salt shakers and ladders today, or is your mind more preoccupied with the upcoming weekend?