Belief in fairy lore may have grown from memories of a small statured, secretive
race of forest dwellers. These small people may have been the early inhabitants
of the British Isles, and, perhaps, other parts of Europe. They would have been
captured by invading tribes (the Celts in Britain and the Germanic tribes in
northern Europe), and were submerged, but not destroyed, retiring into
inaccessible woods to continue living a secretive existence around the town,
farms, and fortifications of their invaders. They may have dwelt in love
turn-covered houses that resembled the green hillocks, as the fairy tradition
supposes them to live in hills, and the green costume often attributed to the
fairy people may have been just a form of camouflage. These people, hating
their conquerors, would have taken every opportunity to strike back, but
resorted to a "guerrilla warfare" instead of risking an open attack. The
murder of travelers, kidnapping, poisoning, as well as other "hit-and-run"
tactics, could have been used in revenge. From these would have grown the
hazards and dangers associated with the fairy folk. They probably had difficulty
making a living in the forest, and may have lived by robbing their "larger
neighbors", which legends have indicated, and, in order for the "neighbors" to
stay in the good graces of these people, those living on isolated farms
customarily left food out at night for them. Also, some of these "little people"
were said to be taken as wives of the larger ones, and stories like "Tom Thumb"
may reflect the fact of some families having the "little people" in their
hereditary background. These little people eventually would have died out or
been completely absorbed into the dominant population, but the memories of them
would remain and as their stories were re-told, they would slowly be transformed
into supernatural beings.
What we call "witchcraft" could have started with these people as well, being
followers of the old pagan gods to resist Christianity, their secretive ways
keeping their ancient beliefs alive. And their skills with herbs and poisons
would give them a reputation for being "magical".
But, except for these stories, no physical evidence has survived (no artifacts,
or bones, or even ruins) to provide the above theory.
Some UFO theoreticians suggest that both the beliefs in UFOs and Fairies sprang
from the same source, though this source is unclear; but an extraordinary number of
parallels can be seen in the stories of UFO encounters and encounters with
fairies.