After carefully reading the 1834 version of "The Rime of the Ancient Mariner" and skimming the 1798 version, choose a passage where you believe Coleridge clarifies his intentions with his 1834 revisions. (Just the addition of the marginal glosses often clarifies his intentions greatly, but you may want to focus on other revisions.)
Perhaps the most dramatic and meaningful extended gloss in the 1834 version (first printed in the 1817 version in Sybelline Leaves) of Coleridge's The Rime of the Ancient Mariner relates to lines in Part the Fourth, which begin with
The moving Moon went up the sky,/And no where did abide:/
Softly she was going up,/And a star or two beside.
At this point, the Mariner is despairing because he is alone, lost, reviled by those around him--the Wedding Guest says, "I fear thee and thy glittering eye,
And thy skinny hand, so brown." In both the 1798 and 1834 versions, the lines I quote above signal the beginning of the Mariner's change from complete self-absorption in his own misery to an appreciation of something beautiful outside himself, the water snakes coiling and swimming in the sea. As he watches them glitter in the moonlight, he "blessed them unaware," an unconscious and generous spontaneous act of love.
In the 1834 version, Coleridge's marginalia for these lines begins with "[i]n his loneliness and fixedness he yearneth towards the journeying Moon." Coleridge implies in this gloss that the Mariner begins to understand that he is like the moon and stars, which "sojourn, yet still move onward; and everywhere the sky belongs to them. . . ." Instead of hating his journey, which seems to have no end, the Mariner begins to understand that his journey may be his home. He is like the moon "and no where did abide." In this gloss, Coleridge makes it clear that the Mariner is achieving a sense of peace with himself, a peace that leads him to reach outside himself and bless the water snakes, which means that he is establishing a relationship with Nature.
Coleridge goes a step further to connect the Mariner with the water snakes by noting that "by the light of the Moon he beholdeth God's creatures of the great calm," ensuring that the reader understands the evolution of the Mariner from a self-absorbed victim to a man who is at peace with his place and who understands his connection to God's other creatures. Coleridge's last gloss on this section--"The spell begins to break"--leaves nothing to the reader's imagination: clearly, the Ancient Mariner's nightmare is over, and the Mariner's rebirth--after having symbolically killed Nature--is at hand.
The marginalia often seem unnecessary and perfunctory, but certain ones, and especially the "moon" gloss, are meaningful in that they not only point the reader to a conclusion but also indicate a mature Coleridge looking at the evolution of the Mariner's journey from Nature-killer to a man who understands and feels his kinship with Nature and, by extension, mankind.