What are the themes of sections 130 and 131 of the poem "In Memoriam"?
Sections 130 and 131 are the final two sections of "In Memoriam," apart from the Epilogue. The sections are roughly arranged by Tennyson to represent the progression of his mourning and grief as he processed the death of his close friend, Arthur Hallam. Both these final sections reflect a type of peace that Tennyson reached and a greater agreement with religious faith than some of the previous sections.
In Section 130, the poet reflects that loving one who has passed away is a different kind of love than loving a living person, and yet it nevertheless grows and remains strong. The speaker senses that his friend who has passed on exists but in a different plane or form than he, the speaker, does. The poet feels his friend's presence in the atmosphere, in rivers, in stars, and flowers. Despite this change in the loved one's nature, the speaker loves him more than ever because the former love for him remains, and his love for the person who is now "mix'd with God and Nature" continues to grow. The speaker seems to find comfort to know that he will never be parted from his friend because of this presence he senses, and he knows that in death he, too, will be of that same essence, so he "shall not lose thee tho' I die."
The final section, Section 131, is an assertion of religious faith that the speaker will eventually be reunited with his loved one who has passed on. The first stanza is a prayer or plea that the general ability that humans have to endure suffering ("living will") should unite with Christ to make humankind better—purifying their deeds. This is a way of saying that human grief combined with religious faith will at last culminate in a blissful reunion of people with their lost loved ones in God. The reference to the "spiritual rock" in the first stanza is a biblical allusion that refers to Jesus Christ; I Corinthians 10:4 states, "and that [spiritual] rock was Christ." In stanza 2 "the one that with us works" probably refers to God or the Holy Spirit. The plea continues, praying "that we may . . . trust with faith that comes from self-control." The poet prays for faith to believe the comfort Christianity promises, namely that "we [will] close with all we loved, and all we flow from, soul in soul." This refers to a time after the speaker's death when he believes he will be reunited with his dead loved one and with God ("all we flow from") in the afterlife.
These final two sections of Tennyson's poem reflect a maturing of his religious faith, and his acceptance of a new way of experiencing his dead friend's presence while he awaits a time in the future when they will be reunited in the presence of God.
The entire poem is a process for Tennyson to go through in order to get over the death of his friend. It can be looked at as the 5 stages of grief. By the time that Tennyson reaches section 130, he is in the acceptance stage. He does not feel like Nature is out to "get him" anymore. He sees the unity in nature at this point. He hears his friend in the air, "where the waters run," and he uses imagery in a natural setting. He realizes that his love has grown for his friend over time, and his friend is now a part of both God and Nature. "Though mixed with God and Nature thou, I seem to love thee more and more."
Since the next section is so long, it is hard to sum it all up for you, but it is still the acceptance as the one before. I've attached the entire poem for you in the second link. 131 is the very last section.