Get out the microscope, because we’re going through this poem line-by-line.
"One morn I miss'd him on the custom'd hill,
Along the heath and near his fav'rite tree;
Another came; nor yet beside the rill,
Nor up the lawn, nor at the wood was he;
- The speaker continues to imagine what the old villager might say about him after he's dead and gone:
- He imagines the villager saying that he missed seeing the speaker one morning in the usual place on a local hillside, along the fields ("heath") by the speaker's favorite tree. (This is probably the beech tree mentioned in Stanza 26.)
- The villager goes on to say that another day passed, and yet he still didn't see the speaker by the brook ("rill") or on the grass, or by the woods. Sounds like something's up…