Analyzing Gaiman's "The Graveyard Book", bibliographer and librarian Richard Bleiler detects patterns of and allusions to the Gothic novel, from Horace Walpole's "The Castle of Otranto" to Shirley Jackson's "The Haunting of Hill House". He concludes that Gaiman is "utilizing works, characters, themes, and settings that generations of scholars have identified and classified as Gothic, ... subverts them and develops the novel by focusing on the positive aspects of maturation, concentrating on the values of learning, friendship, and sacrifice." Regarding another work's assumed connection and allusions to this form, Gaiman himself quipped: "I've never been able to figure out whether "Sandman" is a gothic."