How does this quote relate to a mysterious atmosphere?

For one….Upon its head, with red extended mouth and solitary eye of fire, sat the hideous beast whose craft had seduced me into murder, and whose informing voice had consigned me to the hangman. I had walled the monster up within the tomb!” (Poe).

These words are scary.

red extended mouth
solitary eye of fire
hideous beast

What other words are scary?

seduced me to murder

Yep -- and more

but how does this make the atmosphere mysterious?

The words create a nightmarish feeling in me.

The quote you provided is from Edgar Allan Poe's "The Black Cat." To understand how it relates to a mysterious atmosphere, we can analyze the elements within the quote that contribute to the overall sense of mystery.

1. Symbolism: The "hideous beast" with a "solitary eye of fire" represents guilt and the narrator's conscience. This symbol creates intrigue and a feeling of the unknown, as the actual nature of the beast is left open to interpretation.

2. Descriptive Language: The use of words like "hideous," "extended mouth," and "solitary eye of fire" evoke vivid and unsettling imagery, enhancing the atmosphere of mystery and horror. Poe's attention to detail contributes to the unknown and eerie feel of the scene.

3. Allusion to Murder: The mention of murder adds an element of secrecy and suspense. The reader is left questioning the circumstances surrounding the crime, heightening the sense of mystery.

To fully understand the quote's relation to a mysterious atmosphere, it is essential to read the entire story and explore the context surrounding it. Edgar Allan Poe was a master of creating an eerie ambiance, often utilizing elements of the unknown, suspense, and symbolism.