When I teach Wordsworth’s “Tintern Abbey,” I give students a handout with excerpts from three essays about the poem:
“Everyone knows that "Tintern Abbey" is a sad poem…” Quinney, Laura. “Sensibility, and the Self-Disenchanted Self in ‘Tintern Abbey.’” ELH 64.1
"Tintern Abbey" has a temporal structure of absence and presence which is folded upon itself and projected into the future as we move from memory to imagination: grammatically, the poem moves from the "present perfect," where the "past" is recuperable, to the "future" tense at the poem's close, where the present situation is imagined as already "past."
Lawder, Bruce. “Secret(ing) Conversations: Coleridge and Wordsworth.” New Literary History 32.1 (2001) 67-89.