Demons, changelings and humours – the roots of medieval medicine

The Orkney International Science Festival is always an exciting time of year and since I know next to nothing about physics I take great delight in having everyday phenomena explained to me, such as why the tea always seems to dribble down the spout!


It turns out that it’s called the Coandă Effect and it’s the same thing that makes air flow along the surface of airplane wings and creating lift. I was amazed! I think it’s pretty impressive how many things people have discovered over the centuries – some as sudden strokes of singular genius, but most, I believe, come about like the wren who hid on the eagle’s back and won the high-flying competition by doing only the last little stretch herself.

This made me think about medieval science. In my job at the Centre for Nordic Studies I teach Early Scottish and Norse Literature, among other things. And in these old texts, I sometimes come across references to medieval science; medicine in particular. In the Norse sagas, we occasionally get glimpses of medical practice which I think shows a great deal practical sense when it comes to such things as dressing wounds. For example, in the saga of St Olaf in Snorri Sturluson’s Heimskringla, leek is used in a clever way to find out how deep a wound is:

“The girl said, ‘Let me see your wound, and I will bind it.’ Thereupon Thormod sat down, cast off his clothes, and the girl saw his wounds, and examined that which was in his side, and felt that a piece of iron was in it, but could not find where the iron had gone in. In a stone pot she had stirred together leeks and other herbs, and boiled them, and gave the wounded men of it to eat, by which she discovered if the wounds had penetrated into the belly; for if the wound had gone so deep, it would smell of leek.”

Norse law even details a system of compensation for wounds, here quoted from the Frostathing Law which covered the area around Trondheim in Norway:

“Now bone-payment is payable wherever a bone comes loose from a wound, though it be very small, as long as it rattles [when shaken] in a shield, then one eyrir must be forthcoming. One eyrir is to be paid for each bone up to six, but if so big a bone is removed that six holes can be bored in it, then six aurar are to be paid, but bone-payment is never bigger than six aurar. But if a wound needs cauterizing, then the 'lip-twisting' eyrir is payable, and the same is payable every time cauterizing is necessary. But as physician's fee one eyrir is to be paid every month, and two-months' worth of flour and two of butter. He who did the wounding must pay” (translated by Foote and Wilson).

European medicine at the time was much centred around the theory of the four humours, which has ancient roots. It was systematised as a medical theory by Hippocrates and further developed by Galen. The theory remained popular right through the Middle Ages and into relatively modern times.

The gist of the humour theory is that our bodies contain four basic liquids: blood, black bile, yellow bile and phlegm. Any imbalance in these liquids will cause illness, and the balance may be influenced by such things as diet, occupation, or where you live. Hippocrates linked this idea to the Greek theory of the four elements: that everything is made of water, earth, air and fire. He also made a connection to the opposite qualities of warm and cold, and wet and dry. Water and phlegm was thought to be cold and wet, earth and black bile was cold and dry, air and blood was warm and wet (remember this was in Greece where they have warm air), while fire and yellow bile was warm and dry.

The relative proportion of the various elements in your body was thought to be reflected in your personality. We still speak of someone being “melancholic”, and this disposition was believed to be caused by a dominance of black bile. Those dominated by blood were “sanguine”: a happy, positive and amorous type. Emotional people who are quick to anger were said to be “choleric” and dominated by yellow bile and the element fire, while their opposites the “phlegmatics” were calm and calculating. (It has of course been pointed out on Harry Potter fan sites how nicely J. K. Rowling has adapted the humour theory into four personality types in the Hogwarts houses!)

Within this line of thinking, it’s advisable to monitor your diet so that you don’t disturb the balance too much. I once tried cooking fishcakes from this principle. They seem to be the perfect food. Starting with the fish, they come from water and are therefore cold and wet. Should be perfect for stimulating the production of phlegm in my body. I proceeded to add potato, which is of course an earth thing and therefore cold and dry, which stimulates black bile. At this stage, my fishcakes were too much on the cold side. I needed to balance it up with something warm and dry, so I fried them. I was relieved to see warm and wet vapour emerging in the frying process, proving the existence of all four elements in my fishcakes. They were safe to eat.

In the Middle Ages, of course the terms “bacteria” and “virus” were not in use. But although they didn’t know precisely how it worked, at least they had the idea that illness could be caused by eating or breathing in something invisible. My colleague Victoria Whitworth told me a story about this, which now seems hilarious but which actually has a point. It occurs in the influential book Dialogues which is usually attributed to Pope Gregory the Great and thought to be written around 593 AD. Here, we hear of a nun who is out in the vegetable garden and picks and eats a lettuce leaf without making the sign of the cross first. What she didn’t know, was that on the lettuce leaf a small, invisible demon was sitting. On swallowing him, the nun was of course possessed. After much ado, a priest manages to exorcise the demon and asks him why he possessed the good nun, to which the demon rightly says that he was just minding his own business. He couldn’t help being swallowed!

Closer to home, but thinking along the same lines, was St Columba of Iona who also lived in the 6th Century. In the visionary poem The High Creator where he describes the heavens and the earth and how all creation works together, he says of demons that they are “driven from the midst and thrust down by the Lord” and that the “space of air was choked by a wild mass of his treacherous attendants” who are “invisible” but still everywhere around us, ready to tempt us to sin or make us ill!

The theory of the four humours and the demon lore were educated ways of thinking about medicine, advocated by university lecturers and churchmen. Ordinary folk in these airts had their own medical practices, which included plant and herbal medicine and sympathetic magic such as untying all knots, loosening belts and taking off saddles around the farm to help a woman give birth (this practice is attested as far back as in the Old Norse poem Oddrúnargrátr in the Edda). Disability or disease in young children was explained as the child having been exchanged for a supernatural child. The way to deal with this was to make the changeling expose itself for what it was. Changelings were often older than they looked, so one might for example do something absurd like pour whisky in an egg shell or serve a tiny portion of porridge in a huge bowl, which would make the changeling forget it was supposed to behave like a baby and exclaim “I’ve never seen anything like this before!” or similar. Once exposed, it would return to its own people and if you were lucky you would get your own baby back. I wonder if parents really tried these practices, or if the advice in folktales just belongs in folktales and not in real life?

In the 16th century, a Swiss alchemist by the pompous sounding name of Theophrastus Bombastus von Hohenheim, nicknamed Paracelsus, started stirring up the old humour theory which of course caused great conflict with his contemporary academics. His heresy to the establishment was that he believed in actually studying the body and the chemical substances instead of seeking guidance from old texts, and that he as a physician and university lecturer personally spent time among ordinary sick people instead of letting lesser mortals such as the barbers deal with that. He discovered how to use chemistry to produce effective medicines (alchemy and chemistry was the same thing then, and is also the same word root), and confident that he was right he annoyed everyone around him by bombastically exclaiming: “Every little hair on my neck knows more than you and all your scribes, and my shoe buckles are more learned than your Galen and Avicenna, and my beard has more experience than all your high colleges!”

My husband says he would have been dead twice already if it wasn’t for modern medicine. But the road to modern medicine has been long, winding and at times unpredictable – but also scenic and quirky. Modern physicians can thankfully cure many things which would have caused a painful death in the past. But I wonder what people will discover in the future which would have seemed miraculous to us now? And what among contemporary medical practices will seem as exotic to people of the future as demons, humours and changelings seem to us?

Ragnhild Ljosland, September 2013