The fall of the House of Usher by edgar allan poe

Usher tries to explain to the Narrator that he dreads "the events of the future, not in themselves but in their results." He dreads the intangible and the unknowable; he fears precisely what cannot be rationally feared. Fear for no apparent reason except ambiguity itself is an important motif in Poe's tale, which after all begins with the Narrator's description of his own irrational dread: "I know not how it was--but, with the first glimpse of the building, a sense of insufferable gloom pervaded my spirit." Later, Usher identifies fear itself as the thing that will kill him, suggesting that his own anxiety is what conjures up the blood-stained Madeline--or that she is simply a manifestation of his own deepest neuroses.