What is the author's style in The Imp of the Perverse by Edgar Allan Poe?

For most of this story, Poe's narrator seems to be writing a treatise on the workings of the mind rather than a piece of fiction. Even the sentence which follows seems to be a type of thesis statement.

"In the consideration of the faculties and impulses — of the prima mobilia of the human soul, the phrenologists have failed to make room for a propensity which, although obviously existing as a radical, primitive, irreducible sentiment, has been equally overlooked by all the moralists who have preceded them." (pg. 193)

Poe also uses his command of language to concisely describe what he calls "perverseness," using its definition to explain what he feels is an inevitable human compulsion.