In "The Black Cat" by Edgar Allan Poe, how does the description of the cat as "sagacious" contribute to the meaning of the story?

The description of the cat as "sagacious" adds characterization and tension to the story.

"Sagacious" means "wise," particularly in a shrewd, discerning way. That is, sagacious people and animals can sniff out the truth and make insightful judgments about other people's personalities and motives. It's a word that often describes dogs rather than cats, a word for emphasizing the animals' remarkably keen intelligence, and in fact the narrator of Poe's "The Black Cat" first uses the word "sagacious" in reference to dogs.

So when the narrator goes on to describe the cat as sagacious, we instantly understand that this is not some dumb kitty who happens to belong to the narrator, but rather a sensitive, discerning creature:

"This latter was a remarkably large and beautiful animal, entirely black, and sagacious to an astonishing degree."

Knowing that the cat, Pluto, has penetrating insight, readers tense up, wondering what it is about the narrator that will be exposed through that cat's insight. We're eager to move forward in the text to find out what Pluto's sagacity will reveal.