Question

Which two sentences contribute to the overall eerie mood of the adapted excerpt from "The Fall of the House of Usher" by Edgar Allan Poe?
In this mansion of gloom I now proposed to myself a stay of some weeks. Its proprietor, Roderick Usher, had been one of my closest friends in boyhood. But many years had passed since our last meeting.
A letter, however, had lately reached me in a distant part of the country. A letter from him, which, in its wildly insistent nature, had allowed no other than a personal reply.
The handwriting gave evidence of nervous agitation. The writer spoke of a kind of illness--of a disorder which oppressed him--and of an earnest desire to see me.
As his best and indeed his only personal friend, with a view of attempting, by the cheerfulness of my society, to provide some relief from his malady.