Meter and rhyme must be suited to the poem's content, theme, and tone.
He was not surprised because he was already going insane. Since he was hallucinating that the raven was spouting words at him. He was already ill to begin with so it was not a surprise he thought the raven spoke.
<u>Explanation:</u>
Remember, the English word foreshadowing refers to a brief detail or scene that shows something that will occur again in the future. Indeed, this was the case in "House Taken Over" by Julio Cortazar.
For example, in the story a foreshadow of a shift in the tone of the story begins when we read about Elvio;
“I went down the corridor as far as the oak door, which was ajar, then turned into the hall toward the kitchen, when <em>I heard something in the library or the dining room. The sound came through muted and indistinct, a chair being knocked over onto the carpet or the muffled buzzing of a conversation...</em>I heard it. ....toward the door. I hurled myself against the door before it was too late and shut it...I ran the great bolt into place, just to be safe.”
Interestingly, from that point on the house became taken over by strange noises. In the end, the siblings been fully frightened left their ancestral home, that is when the true meaning title of the story becomes clearer. Indeed, it became a "House Taken Over".