ignis fatuus

From New Latin ignis fatuus (literally “foolish fire”).

• IPA^(key): /ˈɪɡnɪs ˈfætjuːəs/

ignis fatuus (plural ignes fatui)

1. (folklore) A will o' the wisp.
   • 1624, Democritus Junior [pseudonym; Robert Burton], The Anatomy of Melancholy: […], 2nd edition, Oxford, Oxfordshire: Printed by John Lichfield and James Short, for Henry Cripps, →OCLC:

     Fiery spirits or devils are such as commonly work by blazing stars, fire-drakes, or ignes fatui; which lead men often in flumina aut præcipitia, saith Bodine […]

   • 1662, [Samuel Butler], “[The First Part of Hudibras]”, in Hudibras. The First and Second Parts. […], London: […] John Martyn and Henry Herringman, […], published 1678, →OCLC; republished in A[lfred] R[ayney] Waller, editor, Hudibras: Written in the Time of the Late Wars, Cambridge: University Press, 1905, →OCLC, canto 1, page 16:

     An Ignis Fatuus, that bewitches, / And leads Men into Pools and Ditches

2. (figuratively) A delusion, a false hope.
   • 1660, William Petty, Reflections upon Ireland, page 55:

     […] they think this is written on purpose to be published; and that this defence is so published, that it may serve as an Ignis fatuus to mislead them […]

   • 1838, [Letitia Elizabeth] Landon (indicated as editor), chapter V, in Duty and Inclination: […], volume III, London: Henry Colburn, […], →OCLC, page 49:

     He cursed the journey he had been led to take after what had proved but an ignis fatuus, deluded as he had been by false expectations; […]

   • 1908, Henry James, chapter XIX, in The Portrait of a Lady (The Novels and Tales of Henry James; III), New York edition, volume I, Boston, Mass., New York, N.Y.: Charles Scribner’s Sons, →OCLC; republished as The Portrait of a Lady (EBook #2833), United States: Project Gutenberg, 1 September 2001:

     Henrietta’s career, however, was not so successful as might have been wished even in the interest of her private felicity; that view of the inner life of Great Britain which she was so eager to take appeared to dance before her like an ignis fatuus.

   • 1985, Cormac McCarthy, Blood Meridian […] , →OCLC:

     Like some ignis fatuus belated upon the road behind them which all could see and of which none spoke. For this will to deceive that is in things luminous may manifest itself likewise in retrospect and so by sleight of some fixed part of a journey already accomplished may also post men to fraudulent destinies.

   • 2007, Clive James, Cultural Amnesia, Picador, page 805:

     But he was slow – painfully slow, hour after hour slow, sweating and struggling in front of his own class slow – to accept the truth about the simple statement: the truth being that it is an ignis fatuus.