external conflict; the protagonist vs. nature
The author must decide whether his Purpose for writing is to inform, persuade, entertain, or explain his ideas to the reader.
The sentence is saying nonviolence is a powerful weapon that can destroy unrighteousness without even wounding it and can heal everything around it.
Answer:
The line 'So Eden sank to grief' is an allusion, or literary reference, to the Biblical story about The Garden of Eden, a perfect paradise until Eve ate from the Tree of Knowledge. By making this reference, Frost is implying that the idea nothing good can last is an old one; it's part of our human experience.
