What is "love" being compared to in the poem "Love (III)" and how do you know this is an extended metaphor?
At first, it would seem that the speaker is addressing the abstract notion of love. Thus, he is speaking to a personified love and that is why the "L" is capitalized. This reading does not contradict but in fact supports the added meaning that "Love" is God as well. When he speaks to Love, he is speaking to God, but he speaks to the abstract notion of love because God's love is so all-encompassing.
So, in the extended metaphor, he talks to the abstract idea of love but he means God. This is confirmed in the final stanza when he substitutes "Lord" for "Love."
In the first stanza, Love/God welcomes him but he feels unworthy, so he withdraws. Love/God draws nearer and attempts to make him feel welcome. In the second stanza, still feeling unworthy, the speaker says he can not even look upon "thee" (Love/God). God responds that he made the speakers eyes to look upon him. In the final stanza, the speaker answers that this is true: "Truth, Lord." Here, "Lord" replaces "Love" and this proves the extended metaphor that Love is God.
In the end, the speaker finally submits to the idea that he, a human, can not be perfect. This is something that God fully knows and it is why God continues to welcome him even with his imperfections. The idea that God is Love indicates that it is God's nature to necessarily welcome him.
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