In the preface of the second edition, Walpole creates a heuristic for reading Castle which irrevocably changes the way readers are to view the novel until its end. He claims to blend the new and old styles of romance. The "old" romance is what we would consider pre-novel prose – a main tenet of such writings is their fantastic nature. There is magic, the supernatural abounds and they are wholly unbelievable. The style of the "new" romance is what the novels of the 18th century, when Walpole was writing, would generally have looked like. These novels were realistic: they purported to depict events and people as they truly were.
Walpole then, by attempting to blend these two genres, creates something new – something truly "novel". He creates fantastic situations (helmets falling from the sky, walking portraits, etc.) and places supposedly real people into these situations and allows them to act in a "real" manner. In doing so, he effectively allows fiction to evolve in ways that it would otherwise have not been able to. However, readers then may question to what extent did Walpole succeed in his attempt. Do readers view these characters' reactions as truly realistic, or do they merely seem so because of the heuristic that we are given at the outset of the novel?
An additional note: Walpole, in Castle, introduces many set-pieces that the Gothic novel will become famous for. These includes mysterious sounds, doors opening independently of a person, and the fleeing of a beautiful heroine from a licentious male figure.
The Castle of Otranto and Shakespeare
The first and most obvious connection to William Shakespeare is presented by Horace Walpole himself, in the preface to the second edition of Otranto, in which he "praises Shakespeare as a truly original genius and the exemplar of imaginative liberty, as a part of a defense of Otranto 's design". Outside of the preface, Walpole uses several allusions to works by Shakespeare as further emphasis of the connection he wishes to be found between his own work and that of Shakespeare. For example, in Hamlet, "Hamlet's encounter with the Ghost becomes for Walpole a template for terror".
Walpole presents a "more fragmented recasting" of the Ghost in Hamlet, which had served as a representation of the "now unsanctioned, but still popular Catholic view of ghosts as speakers of truth" for Shakespeare The Catholic elements at play within both Hamlet and Otranto are both invoked to represent a further sense of wonder and mystery to the Protestant audience of both works. The Catholic element was a necessary facet of the "template of terror" that Walpole meant to invoke.
The allusion to Hamlet's experience with the Ghost is meant not only as a "template of terror", but also serves to make the reader invoke the feeling of watching the play itself and he does so on three separate occasions. First, Walpole poses Manfred's encounter with the animated portrait of Ricardo as a connection to the Ghost's initial appearance to Hamlet. Second, when Friar Jerome informs Theodore of the dangers to be found in Otranto and he calls for him to take out his revenge correspond to the Ghost's demand to Hamlet to "remember [him]". Third, Frederic's encounter with the skeletal apparition parallels the final appearance of the Ghost in Hamlet.
The violent question of bloodlines and succession is one that serves as a key element in many of Shakespeare's plays, spanning from Hamlet to Richard II and Macbeth, and it is one that is clearly one of the major concerns of Otranto. The link to Hamlet is strengthened even more because of the matter of incest that is also at play in Otranto. "In Otranto, the castle and its labyrinths become grounds for incest that signal the dissolution of familial bonds", which is also a major point of issue in Hamlet since Hamlet's mother (Gertrude) and his uncle (Claudius) were, in a way, related before their marriage. Both Hamlet and Otranto are literary springboards for discussion on the questions of marriage, as the question of Henry VIII's annulment of his marriage and later marriage to Anne Boleyn were still heated topics of controversy. Henry VIII had both married his brother's wife Catherine of Aragon and later dissolved that marriage due to Catherine's inability to produce a male heir that lived to adulthood. Similarly, Otranto revolves around "a larger sexual contest to secure lineage". Henry VIII dissolved the marriage on grounds that the marriage between Catherine and his older brother, Arthur, had not been consummated. Both Hamlet and Otranto show echoes of this story as major elements within the framework of each literary structure.
The final connection from Otranto to Shakespeare lies in the role that the servants play. Like Shakespeare, Walpole aims to create a "mixture of comedy and tragedy" and one of the ways he does so is by using the minor, servant characters (such as Bianca) as comic relief. This is a trope that Walpole takes from Shakespeare. For example, Shakespeare's mechanicals from A Midsummer Night's Dream also serve as the key comic element.