Haunted Man and the Ghost's Bargain

Redlaw is a teacher of chemistry who often broods over wrongs done him and grief from his past life. He is haunted by a spirit, who is not so much a ghost as Redlaw's phantom twin and is "e;an awful likeness of himself...with his features, and his bright eyes, and his grizzled hair, and dressed in the gloomy shadow of his dress..."e; This spectre appears and proposes to Redlaw that he can allow him to "e;forget the sorrow, wrong, and trouble you have known...to cancel their remembrance..."e; Redlaw is hesitant at first, but finally agrees. However, before the spirit vanishes it imposes an additional consequence: "e;The gift that I have given you, you shall give again, go where you will."e;(Excerpt from Wikipedia)