Lisa Shiel has a new, three-part feature at her Backyard Phenomena blog called The Invisible World.
In part one, Lisa begins: "All paranormal phenomena are connected. I can't prove that statement. But when you study the paranormal for very long, strange things start to pop out at you. Paranormal phenomena often cluster in certain areas, or around certain people. Bigfoot, UFOs, poltergeists, fairies...the lines between them begin to blur. The phenomena also share traits in common: the ability to appear/disappear at will; a tendency to abduct humans; the belief by percipients that the phenomenon will impart some great wisdom to them; a long, worldwide history of legends and sightings; an elusive quality that makes scientific study of the phenomenon impossible. The list could go on and on. I also see another aspect common to all the phenomena—they seem to come from 'elsewhere.'"
With that, I most definitely agree.
Here the links to the relevant parts of Lisa's feature: Part One; Part Two; and Part Three.