Final answer:
Certain key words in the passage help create an unsettling mood, such as "vacant eye-like windows" and "rank." These words have denotations and connotations of darkness, emptiness, abandonment, and decay, which contribute to a sense of gloom and depression. Analyzing the connotations behind the words can lead to a deeper understanding of the passage's mood.
Step-by-step explanation:
When reading a passage like this, you might get a general impression that its mood is gloomy and depressing. Certain key words in the passage are what create that impression, and if we look at the italicized text, we can see a pattern.
The narrator is describing a house, but "vacant eye-like windows" has a denotation of dark or empty windows, but it also brings up the connotation of corpses. "Rank" means overgrown, but it brings up connotations of abandonment and possible decay. Continue looking at the connotations behind each word, and see if you can detect any patterns.
For instance, do the italicized words in this passage make you think of death, decline, and decay? Does the comparison to "the after-dream of the reveller upon opium" make you question the narrator's state of mind? By asking these kinds of questions, you're on your way to doing a close reading.