The Psychology of Fear
The novel is a ghost story, after all, so fear should naturally be a dominating theme. What is especially interesting about how the author handles this theme, however, is that she reveals the insidious process by which a rational reaction to fear devolves into the irrational. It is this slow, deliberate process that transforms Arthur from a basically normal young man into a soft puddle of almost psychotic paranoia who no longer has any control over the effects of being terrorized.
Maternal Vengeance
At the heart of the novel’s plot is stimulation of vengeance by a woman whose most precious gift has been taken from her. Vengeance over deprivation is a time-honored subject; Hamlet is really about a son who embarks upon revenge because his father has been taken from him. Being deprived of a father at a young age—even as advanced a young age as Hamlet—would be bad enough, but surely that would nothing like losing an infant. The bloodlust for revenge under these circumstances—no matter the quirkiness of the details and specifics—is an understandable enough reason for ghost to go a-haunting.
Isolation
The theme of isolation is common to such ghost stories, stretching from the earliest gothic novels to Stephen King. Because time is such a significant element to the story, the isolation of Eel Marsh House does not come across stereotypical or lazy plotting, but is instead integral to the story. Being cut off from society, the very inaccessibility of the setting stirs the psychological effects of fear upon Arthur by its very remoteness. Thematically, that remote quality also applies to the ghost which haunts him.
The Ghosts of Time
The novel continually plays with time to pursue themes related to how the past intrudes upon the present to create a continuous line. The novel is structured as a story-within-a-story which introduces the concept of past and the present being connected. The isolated house is also show to be haunted irreversibly steeped in the decisions of the past through Mrs. Drablow’s collection of documents. And, of course, both Arthur and the demonic ghost terrorizing him are haunted by traumatic memories of earlier times. Even the language of the novel itself is a revelation of this continuous line of time as it speaks to an outdated formality that does not seem to fully jibe with its period setting.