After a tumultuous trip to Denmark to retrieve his bride following a proxy marriage in 1589, King James the VI and I allegedly became obsessed with demons, witches, and the Devil. At the time, witch-hunting was common in Scandinavia, and James reportedly attributed many of the problems he faced on his trip to demons. In order to further explore the horrors of the underworld, he retreated to Scotland, where he wrote what he believed to be a discourse on the “science” of demons. The book, Daemonologie, debuted in 1597. On top of being the only book of its kind published by a member of the monarchy, it spurred the witch hunts that impacted Europe and the American colonies in the 17th century.
In Daemonologie, King James breaks down exactly how to spot a demon and explains how they possess someone. However, his book doesn’t simply deal with demons. He also dives into the existence of fairies, witches, and werewolves - all with the same mannered, scientific prose. James’s writings are at times far-fetched, and while most of his thoughts on the supernatural are now considered archaic, much of what he put to paper in his dissertation formed the basis for modern conceptions of demons.
James's text sometimes describes demons in ways that seem straight out of movies like The Exorcist. According to Daemonologie, demons will often take over bodies and force their way into houses. As creepy as that sounds, his text is even more terrifying. James writes:
For if they have assumed a deade body, whereinto they lodge themselves, they can easely inough open without dinne anie Doore or Window, and enter in thereat.
Furthermore, he claims a demon can take over a form that once belonged to an upstanding member of the community and, in doing so, instill anxiety in the populace.
According to the king, one of the major tell-tale signs of possession is when someone is incredibly strong:
I account the one of them to be the incredible strength of the possessed creature, which will farre exceede the strength of six of the wightest and wodest of any other men that are not so troubled.
James describes possessed individuals as having impenetrable skin as well:
And such an ironie hardnes of his sinnowes so stiffelie bended out, that it were not possible to prick out as it were the skinne of anie other person so far.
In Daemonologie, James describes the way demons use the bodies of a person's perished loved ones to prey on them. James specifically posits that demons are able to take over the bodies of the genuinely pious because the soul is clean and the body is dirty. He writes that demons inhabit the forms of friends, family members, or famous people in order to speak to people and trick them into doing the bidding of the Devil.
Scholars assert James's reasoning for this is a way to explain why people claimed to see friends and family members they knew to have passed.
Modern Christians are divided on whether or not speaking in tongues constitutes demonic possession, but James was less concerned with languages from the beyond and more with people speaking a language other than English. According to the king, one of the main ways to tell if someone is a demon is the "speaking of sundrie languages" that the possessed never could have learned on their own.
This belief likely comes from the fact that people in the 16th century were typically isolated and often illiterate even in their native language; a person had to be incredibly well-educated to speak a second language.