Jacob Marley had been Ebenezer Scrooge's business partner until his death seven years prior. He appears to Scrooge as an apparition at the beginning of Scrooge's dream. Dragging heavy chains and appearing "like a bad lobster in a dark cellar," Marley proceeds to warn Scrooge that, unless the latter changes his attitudes and outlook on life, he, Scrooge, will end up like him: forced to walk the afterlife forever dragging the heavy chains of sin and regret. Before vanishing, Marley tells Scrooge that he will be visited during the night by three ghosts, messengers intended to convey the final warning for Scrooge to amend his ways.
In the Charles Dickens' Christmas Carol, Marley was Scrooge's collegue. He's now dead. His spirit warns Scrooge of the 3 Christmas spirits who have yet to come.
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