Free Folklore of Discworld by Terry Pratchett

of the country, those people know they are real. And they remember that though they might , just occasionally, bring good luck, they are far more likely to inflict diseases, kidnap people, and steal human babies, replacing them with their own sickly and mentally deficient ‘changelings’.
    Changelings were a particularly sad obsession. A healthy young couple out in the country and in a world without modern medical understanding or any idea of the meaning of the term ‘limited gene pool’, give birth to a child who looks like a little old man, or is beautiful but very backward, or eats incessantly but nevertheless fails to thrive … and the only reason the family can find lies in folklore: ‘the fairies stole our beautiful child and left one of their own.’ A horrible thought, yet not quite so horrible for the parents as one religious alternative: ‘It’s our own fault the baby is like this, it’s a judgement on us for our sins.’
    In a disturbing but fascinating paper published in the journal ofthe Folklore Society in 1988, Susan Shoon Eberley cites many accounts of the appearance and behaviour of changelings as they were described in nineteenth-century sources, and maps them against dozens of childhood disorders which produce children that look and act ‘like the fairies’. The Victorian medical establishment was coming to grips with the idea that these children were victims of disease; but the common people fell back on folk myth, which was reinforced with every case.
    Folk myth also supplied a cruel remedy. You had to make life so miserable for the changeling that it would flee and the ‘real’ child would miraculously return. Custom handed down various ‘remedies’, including putting the child in a hot oven or leaving it out on the midden all night – child abuse at best, socially condoned infanticide at worst. The wonderful child did not return, but at least there was no longer the inconvenient changeling in the cradle, and everyone nodded and understood …
    Nanny Ogg, a midwife, knew what she was doing when she took the king of the elves to task in Lords and Ladies . A society does not want elves in the driving seat.
    Yet by the nineteenth century, in much of Europe, memories were fading, and people spoke of elves and fairies without such fear. Their world was under attack by education and street lights and medicine and technology; the telegraph could beat Puck when it came to putting a girdle round the earth.
    And thus their decline continued. Though people still told stories about changelings and abductions, on the whole they believed (or half believed, or suspended disbelief) that the Hidden Folk could be good neighbours to humans, and were just mischievous, not truly dangerous. They could lead you astray even in woods which you knew quite well, so that you felt hopelessly lost and would maybe fall into a ditch, but that was just their fun (and in any case it was easier to blame the fairies than the cider). They would do you no harm, provided you were careful not to offend them. The rules were clear: don’t cut down their favourite trees, don’t damage the mounds wherethey live, don’t build a road across their paths, be careful where you throw dirty water, keep your house clean and your hearth swept in case a fairy comes there in the night.
    There was even one type, the house-elves, whom humans welcomed. The English called them hobs, pixies or pucks, the Scots brownies, the Scandinavians nisses and tomtes. These would actually live in a farm and bring it luck; they would help with harvesting, tend the animals, even do housework, in exchange for an occasional bowl of milk or porridge – provided nobody spied on them or laughed at them. Russian country folk said there were several on each farm; the most important one lived behind the stove, others guarded the barn, the bath-house, the henhouse, and so on. On the Discworld, only the Wee Free Men have ever done such a favour for humans, and then