 For contemporary viewers, "The Nightmare" invoked the relationship of the incubus and the horse (mare) to nightmares.The work was likely inspired by the waking dreams experienced by Fuseli and his contemporaries, who found that these experiences related to folkloric beliefs like the Germanic tales about demons and witches that possessed people who slept alone.In these stories, men were visited by horses or hags, giving rise to the terms "hag-riding" and "mare-riding", and women were believed to engage in sex with the devil.