Why is Wedding Guest in "The Rime of the Ancient Mariner" a sadder and wiser man after hearing the Mariner's story?
I need to have three reasons. I already have two, I just can't think of the third one.
When the Wedding Guest is accosted by the Mariner, he is irritated and frightened. Once the story is underway, the Wedding Guest is mesmerised. By the end of the tale, he is sadder and wiser. His responses - fear at being accosted by such a strange man, fascination at such a bizarre story, sadness and reflectiveness in reaction to the Mariner's fate and his message - certainly seem plausible.
To me, the key reason why he is a sadder and wiser man is that he has learnt and taken to heart the moral of the tale:
He prayeth well, who loveth we;l
Both man and bird and beast.
He prayeth best, who loveth best
All things both great and small;
For the dear God who loveth us,
He made and loveth all.
It seems to be that the main theme of this ballad is that Nature exacts its own revenge for crimes committed against it and that it is essential to love all creatures. The Wedding Guest is a "sadder and wiser man" because he recognises that this theme of respect for all life is a lesson that humanity must continually relearn.