A walker in the woods stops at a tree and knocks on it, half-hoping something will answer. The speaker is curious and a little playful, treating the tree like a front door. Nothing appears at first. Instead, a breeze shakes acorns loose, and the poem pays attention to their soft thumps as they land on wet moss. The sound is muffled, as if the forest is keeping its voice low.
Then the poem slips inward, to a dream from the night before in which falling felt wonderful rather than frightening. The poem doesn't explain the link, but the falling acorns make a quiet echo of it: things drop, and nothing bad happens. The ending is a small, funny surprise. A cranefly sits among the toadstools, "perched aristocratically," like a guest who has finally answered the knock. The mood is gentle, relaxed and observant, a sense of being at ease in a small, quiet corner of the world.