I reined my horse to the precipitous brink of a black and lurid tarn that lay in unruffled lustre by the dwelling, and gazed down--but with a shudder even more thrilling than before--upon the remodelled and inverted images of the grey sedge, and the ghastly tree-stems, and the vacant and eye-like windows. (1)
This is the second time that the narrator has used the words “vacant” and “eye-like” to describe the house of Usher.
I was aware, however, that his very ancient family had been noted, time out of mind, for a peculiar sensibility of temperament, displaying itself, through long ages, in many works of exalted art, and manifested, of late, in repeated deeds of munificent yet unobtrusive charity, as well as in a passionate devotion to the intricacies, perhaps even more than to the orthodox and easily recognisable beauties of musical science. (3)
This background, too, makes the Usher family seem other-worldly – their world is the fictional world of art and music, not of reality.
"House of Usher"--an appellation which seemed to include, in the minds of the peasantry who used it, both the family and the family mansion. (3)
This line gives us a hint to interpret the title as referring both to the physical house collapsing and to the metaphorical “fall” of the Usher family.
I had so worked upon my imagination as really to believe that about the whole mansion and domain there hung an atmosphere peculiar to themselves and their immediate vicinity--an atmosphere which had no affinity with the air of heaven, but which had reeked up from the decayed trees, and the grey wall, and the silent tarn--a pestilent and mystic vapour, dull, sluggish, faintly discernible, and leaden-hued. (4)
This atmosphere is like a physical manifestation of the mood Poe creates in his story.
"Her decease," he said, with a bitterness which I can never forget, "would leave him (him the hopeless and the frail) the last of the ancient race of the Ushers." (13)
This is the end of the line for the Ushers – the fate of the entire family blood line lies with the fate of Roderick and Madeline.
A striking similitude between the brother and sister now first arrested my attention; and Usher, divining, perhaps, my thoughts, murmured out some few words from which I learned that the deceased and himself had been twins, and that sympathies of a scarcely intelligible nature had always existed between them. (24)
This passage suggests a sort of supernatural connection between the two twins. This connection, we will soon see, transcends even death.