Here's a breakdown of the key elements that contribute to this tone:
* The speaker's suppressed anger: The poem describes how the speaker, initially unable to confront his foe directly, internalizes his anger and resentment. This creates a sense of simmering rage, building towards a destructive outcome.
* The imagery of the poison tree: The growing tree, nurtured by the speaker's suppressed rage, serves as a chilling metaphor for the destructive power of unaddressed anger. The tree's poisonous fruit symbolizes the poisonous consequences of such bottled-up emotions.
* The speaker's actions and thoughts: The speaker actively "watered" the tree with his anger and "sunned" it with his "hate." This deliberate nurturing of the tree suggests a malicious intent, further enhancing the ominous tone.
* The final stanza's irony: The speaker's "friend" is the one who ultimately suffers the fatal consequences of the poisoned fruit. This ironic twist underscores the dangers of internalized anger and the way it can inflict harm on others.
The overall tone of the poem is one of dark foreboding, foreshadowing the destructive power of unchecked anger and the potential for harm to others. The poem's stark imagery and chilling irony leave a lasting impression, warning against the consequences of suppressing our negative emotions.