Eggshells and Changelings

The classic resolution to the story of the changeling: A fairy doppelganger has posed as a human baby and successfully pulled the wool over its human hosts' eyes. However, someone (typically the mother) realizes what's happened. To trick the changeling, she uses empty eggshells as milk pans, stewpots, or brewing cauldrons. The fake infant is so surprised that he suddenly begins to speak. Sometimes he is startled, sometimes amused. "I have never seen the like of that before" is the most common exclamation, as he unthinkingly reveals his great age. Then, in a flash, all is set right and the real baby is returned.

​This story is widespread throughout Europe. But why? What is the significance of eggshells? 

Bear in mind that people actually believed in changelings well into the 20th century. Other remedies for a changeling were things like putting it on a hot shovel, leaving it out in the elements overnight, or threatening the suspected elf with torture. In an infamous 1895 case, a man named Michael Cleary killed his sickly wife Bridget, insisting that she was a fairy and his real wife had been taken away. He was found guilty of manslaughter.​ There were other such cases that made it to the news and incited outrage, and probably far more that were never publicized. As suggested by D. L. Ashliman, changeling beliefs may have been a more palatable excuse to kill a disabled relative who was seen as burdensome.

The eggshells are a gentler method. Rather than threatening the child in brutal ways which remind of real practices, this story is more palatable. The parents need not threaten anything wearing the face of an innocent baby. The changeling is ancient and manipulative, but it is still possible to trick it. It reveals itself and (usually near-instantly) the problem is solved. Even if beating it or leaving it on a trash heap overnight is still required, the parents now know for sure that they are torturing a monster and not their own flesh and blood.

There are plenty of superstitions regarding eggs, and the shells were often associated with witches and fairies. Pliny in the 1st century makes a reference to breaking eggshells, apparently to protect against magical harassment. At least by 1584, in Reginald Scot's Discoverie of Witchcraft, there was an elaborate explanation: witches and fairies used eggshells as boats or houses. In one case, a witch was accused of sympathetic magic using eggshells in a cauldron to simulate ships at sea, then wrecking real ships by stirring the cauldron. In this tradition, the shells are associated with sympathetic magic. They are a simple tool easily subverted by dark forces and used for mischief. 

In Waldron’s Description of the Isle of Man, a mermaid says that humans "are so very ignorant, as to throw away the water they boil their eggs in." 

Campbell's Superstitions of the Highlands and Islands of Scotland (1900) tells us that "water in which eggs have been boiled or washed should not be used for washing the hands or face." This is highly unlucky. Also, it was an idiom for someone who'd done something dumb to say "I believe egg-water was put over me."
Campbell mentions a man who asked a mermaid "what virtue or evil there was in egg-water . . . She said, 'If I tell you that, you will have a tale to tell.'"

One possible explanation: according to Legends & Superstitions of the County of Durham (1886), washing in egg-water causes warts. 

On the other hand, the accused witch Elspeth Reoch, in 1616, said that fairies had instructed her to roast an egg and use its sweat to wash her hands and rub her eyes, which would give her any knowledge she wished.

I wonder if there is some connection from the egg to birth and babyhood. Most changeling traditions focus on newborns, the days after birth, the period before christening. The changeling is posing as an infant too young to speak. Eggshells are a symbol of new life, and the fairies have choked off life from the family's home by stealing the newest life there.

However, eggshells in changeling tales are also somewhat random. Anything, not just eggs, can be used by humans to bewilder fairies.  In an Icelandic tale, a woman binds rods to a spoon to create a long handle, confusing the changeling into exclaiming, "Well! I am old enough, as anybody may guess from my beard, and the father of eighteen elves, but never in all my life, have I seen so long a spoon to so small a pot."

Even when the stories do feature eggshells, they may be used in different ways. They may be left in front of the changeling as-is, or used as pots to boil water or cook food.

Sir Walter Scott retold a Scottish tale where a fairy changeling spoke up when left alone with twelve eggshells all broken in half. In this case, the bewildered fairy says it has "Seven years old was I before I came to the nurse, and four years have I lived since, and never saw so many milk pans before." In this case, rather than the human parent confusing the fairy by telling them they're making dinner in an eggshell, the fairy itself misidentifies the shells. This points to traditions where fairies live inside eggshells and use them as boats, or where fairies are extremely miniature.

In at least one case, fairies seem disturbed and possibly even offended by such behavior. In "The Egg-Shell Dinner," collected by Thomas Crofton Croker, a farm is plagued not by changelings but by mischievous spirits. A wise woman instructs the farmer's wife to boil a tiny amount of pudding in an eggshell, ostensibly as a meal for six hungry farmworkers. The fairy-poltergeists announce,
"We have lived long in this world; we were born just after the earth was made, but before the acorn was planted, and yet we never saw a harvest-dinner prepared in an egg-shell. Something must be wrong in this house, and we will no longer stop under its roof." 
 
Sometimes the eggshells themselves are boiled in water. In Thomas Crofton Croker’s version of the “Brewery of Eggshells,” the mother is told to “get a dozen new-laid eggs, break them, and keep the shells, but throw away the rest; when that is done, put the shells in the pot of boiling water.”
The fairy has reversed the way things should be – a cunning, articulate, ancient being behaves like a baby too young to speak. So the human family performs another reversal. In a nonsensical and wasteful display, the mother throws away food and cooks garbage. Once the changeling is gone, things may return to their normal state.

​In nearly all cases, there are mentions of how the changeling does nothing but eat ravenously - screaming for milk or eating the family out of house and home. Therefore, in some versions, the eggshell theme makes it clear that there is now an end to the changeling's "free ride," which prompts them to call it quits. 
In Ireland: Its Scenery, Character, &c, vol. 3, people suggest getting rid of a changeling by this method: "to make egg-broth before it, that is, to boil egg-shells and offer it the water they were boiled in for its dinner, which would make it speak at once."
And in a Danish tale, a girl serves a voracious changeling the most inedible pudding possible, containing bones and pighide. He declares, "Well, three times have I seen a young wood by Tis Lake, but never yet did I see such a pudding! The devil himself may stay here now for me!" With that, he's gone.
So inedible or unappetizing food drives off the changeling who is just using the family for a free meal. (At the same time, this is tacit permission to starve the troublesome child who isn't thriving.)

Also note that whether or not the ritual includes an eggshell, it is still nearly always associated with cooking. This could be a memory of real-life rituals in which "changelings" were treated by being burned. Rather than putting the changeling itself into the fire, the changeling is forced to watch something else being heated in the fireplace. There's an implicit threat.

In cases where the Slavic water demon Dziwożona or Boginka sometimes left changelings, human mothers were to take the changeling to a garbage heap, whip it with a rod, and pour water over it using an eggshell, all while calling to the Boginka to "Take yours, return mine!"
(Madrej glowie dość dwie slowie, Krzyżanowski, 1960, p. 73) Perhaps this is a confusion of the eggshell story with the idea of torturing a changeling.

Similarly, in 1643, accused witch Margaret Dickson had performed  healing rituals which suggest she attributed sicknesses to fairy changelings. After her attempt to heal a sick child had no effect, she told its mother to throw it onto the fire because "the bairne was not hirs" and was really a hundred years old. The mother ignored this advice and the child began to recover. 
In a second case, Dickson advised a man to place meal baked with twelve eggs in front of a fire, and his crippled child on the other side. Then he was to walk around the house, calling the spirits to "give me my daughter againe, and if the bairne mend the bread and egges wald be away, and if not the shells and bread wald be still." Was this an offering - a trade of food for the return of the healthy child? (Scottish Fairy Belief: A History, pg. 97)

These stories are rationalizations, excuses. Note that in nearly all of these tales, the changeling isn't just a fairy baby, but an ancient, malicious, cruelly clever being which takes joy in the human parents' agony.
Many changeling tales end with the note that even after the ordeal of burning or beating, the rescued child is frail or physically changed. This is explained as the result of its time in Fairyland... but... well... Look at the story with historical cases in mind, and it becomes very dark indeed.

I much prefer the modern story "The Changeling" by Selma Lagerlöf, where the mother's tender care for the changeling - and her absolute refusal to torture it -  convinces the trolls to return her real son.
I also like the Orkney tale of the Rousay Changeling, where a woman recovers her child by tracking down the fairy who took him, and smacking said fairy in the face with a Bible.

It should be mentioned that not all suspected changelings were harmed. As mentioned, one of Margaret Dickson's "patients" apparently flat-out refused to follow her advice. In a few stories, we hear that human parents who took care of their fairy fosterlings were blessed with good fortune (as in the tale of the Changeling of Sportnitz). Another Scottish witch, Jonet Andirson, confirmed to a suspicious father that his child was a "sharg bairn," but told him that so long as he had that sick child in his house, he would not want - i.e., if he was good to the fairy child, his family would be taken care of. (The Register of the Privy Council of Scotland, vol. 8, p. 347)

Further Reading

• Witches, Fairies, Eggshells and Sieves