"The idea of parting from you, never seeing you again, pierced my heart like a red-hot dagger" (Similie)
Clara writes this to Nathanael in the second of the letters that begin the story. Hoffmann often uses similies and metaphors to enrich the imagery of emotions, and the fact that Clara writes of something piercing her heart also builds on the undertones of horror that permeate the story from its outset.
"Your friends' matter-of-fact questions were like gusts of icy air blowing on your inner glow and wellnigh extinguishing it." (Similie)
This quote can be found in the narrator's section on writing, and again uses visceral imagery to better communicate emotion.
"Madness seized him with its red-hot claws and entered his heart, tearing his mind to pieces." (Metaphor)
Hoffmann's similies, metaphors, and imagery are especially compelling when describing fits of madness in the story. This passage especially focuses on the sudden intensity of a fit of "madness."
"Every accusing word threw sparks into his mind" (Metaphor)
This quote describes Lothar's feelings after Nathanael pushes Clara for the comment she makes on his terrifying poem. It is important that sparks are thrown into Lothar's mind rather than his heart, as this reinforces Lothar's character as ruled by logic and propriety, rather than by emotion.
"Nathanael woke, as though from a terrible nightmare" (Similie)
It is important that this is a simile and not a metaphor, because the fantastic nature of the story is such that the reader is still not entirely sure the story has not been a dream. The use of "as" drives home the idea that the nightmarish situation has been reality, however strange and warped the situation.
