To capture the tension between passion and reason within the excerpt, Brontë relies on the use of a fire motif.
Fire here is one thematic element which appears alive and devouring her at the moment of passion and then after the flames are dead when her mind is calm.
Parallel sentence structure uses words to show that ideas are of similar importance, normally they will show the same pattern, we don't see this here. While straightforward, literal language will not use metaphors, as she does comparing her mind with " A ridge of lighted heat". Lastly understatement and irony the writer will play down a situation, making something less important than it actually is.