Three tiny moments from a hot day, each caught the way a person might notice them while standing very still. A leaf drifts down in a slow spiral. A black butterfly sits with its wings still damp, as if it has just climbed out of a tomb. A breeze cools the air, and a warbler sings a song that isn't its usual one.
The speaker mostly watches rather than comments, and that quiet attention is the feeling at the heart of the poem. There's a gentle wonder in it. The butterfly image stands out: "the tomb" suggests a cocoon, but it also hints at death and rebirth, so something ordinary becomes a little uncanny. The leaf's fall hints at endings, yet the butterfly and the song suggest new life. The mood is hushed, patient and slightly mysterious, like a pause in the middle of the day when the world seems to reveal small secrets to anyone who's paying attention.