To see faint lights hovering and slipping about near the ground on a dark night would be enough to scare anybody travelling through a marsh. No wonder the sightings gave rise to superstitious beliefs everywhere that they have appeared. There are many words for them, including the old sense of jack-o’-lantern and the learned Latin ignis fatuus, the foolish fire, as well as will-o’-the-wisp.
Attempts to approach the lights result in them seeming to recede or vanish, only to appear somewhere else. So people thought they were the work of a mischievous sprite trying to lead unwary travellers astray.
But mind, the mountain’s magic-mad tonight,
And if you choose a will-o’-the-wisp to light
Your path, take care, ’twill lead you all astray.
The Magic Mountain, by Thomas Mann, 1927. The translator, H T Lowe-Porter, took the text from an 1884 translation of a verse from Goethe’s Faust.
The belief in sentient forces at work is why there are personal names involved — Will and Jack. Will-o’-the-wisp was originally Will with the wisp, wisp here meaning a handful of hay, presumed to be alight.
We know now that the flames are methane (marsh gas), ignited by the traces of hydrogen phosphide sometimes found near decaying organic matter. Both will-o’-the-wisp and ignis fatuus are used figuratively for some false idea or influence that leads people astray.
Although the meeting passed off politely enough, the occasion was never to be repeated — for the very good reason that the chancellor viewed “the project” as a will-o’-the-wisp with which he was totally out of sympathy anyway.
Sunday Times, 23 Sep. 2001.