A Poison Tree
How we cite our quotes:
I was angry with my friend;
I told my wrath, my wrath did end. (1-2)
The rhyme between "friend" and "end" suggests that, perhaps, it is much easier for anger to "end" when it comes to friends, rather than enemies. Perhaps friendship is necessary before anger can finally subside.
I was angry with my foe:
I told it not, my wrath did grow. (3-4)
If the rhymes in the first two lines emphasize the connection between the end of wrath and friendship, lines 3-4 emphasize just the opposite. The word "foe" rhymes with "grow," which suggests that having enemies, or even perceiving someone as your foe, is the source from which destructive anger springs.
And I watered it in fears,
Night and morning with my tears;
And I sunned it with smiles,
And with soft deceitful wiles (5-8).
The repetition of "and" three times in this stanza suggests how things like anger and "fears," "tears," and "soft deceitful wiles" are connected. The list-like effect of the word "and" implies that all these things are on equal footing with one another, connected in a chain of negativity.