Poems employing the dejection-to-elation structure move from sadness to happiness. Note that there often is some sort of “trigger” for this kind of emotional transformation.
Here’s one of the purest uses of this kind of structure:
Though not as well-known as some other letters, one of my favorite letters by John Keats is the one he writes to Mrs. James Wylie, the mother of his sister-in-law, Georgiana. Georgiana has moved with Keats’s brother George to American. Keats writes to comfort Mrs. Wylie in the wake of her daughter’s absence. The letter initially refuses consolation, but then turns beautifully to employ humor in order, to use Keats’s own phrase, to tease Mrs. Wylie out of her thought. For this letter, click here. If this does not take you right to Keats’s letter to Mrs. Wylie, that letter is dated 6 August 1818, and it begins on page 139.
Here’s another very famous example–though what’s very interesting here is that the transformation (which begins in stanza 3) doesn’t really get a chance to take hold.
Another great example of the dejection-to-elation structure is
“North Jersey Farmland, Vile Mood,” by J. Allyn Rosser (in Misery Prefigured (Carbondale, IL: Southern Illinois University Press, 2001): 62-3).
Like Hardy’s version of this structure, Rosser’s turn to elation is not 100% successful–the poem’s speaker is not quite fully raised into unutterable joy, but remains, to a certain extent, distant from that joy, skeptical of it.