“I was angry with my friend, I told my wrath, my wrath did end. I was a angry with a foe, I told it not, my wrath did grow.” Here the narrator is explaining how he was able let go of the anger he had towards his friend because he expressed his emotions to his friend. On the contrary the anger he had towards an enemy was repressed and as a result it began to take him to a dark place. Just this stanza alone expresses a lot of emotion something that Romantics were known for.
The next quatrain is very important. It explains how he begins to fuel the anger or as he states “water” the anger, causing it continue to grow. He explains how he sunned it with smiles. This could be interpreted in many ways but I think he means the more he pretended there was no animosity the worse it got, his smiles played the role of the sun in helping this strong emotion amplify. “I watered it in fears, night and morning with my tears, and I sunned it with smiles and with soft deceitful wiles.” If feelings of anger or hate are not resolved they will begin to manifest.
He then talks about how the anger he has for his enemy matures into a tree, a poison tree to be exact. When someone lets anger consume them, it is like a poison. He describes how the tree then produces a vibrant apple that his foe decides to covet, because he knows it belongs to the narrator. “My foe beheld it shine, and he knew that it was mine.”
The last quatrain describes the foe dying from the apple....