The poem begins with a small, sudden event: the speaker runs over a hare while driving home. Nothing more is told about the scene, and the bareness is part of the effect. The accident hits us the way it hit the driver, without warning or explanation.
What follows is the speaker's shock. "Tell me I will be her tomorrow" suggests an uneasy sense that the killer and the killed can swap places, that the speaker could just as easily be the one struck down. The "thin ink" is hard to pin down, but it seems to point to how fragile life is, or perhaps to the faint, hurried way the poem itself is written. The heart, we're told, "cannot help" it.
The last lines turn the death into something larger: there is "no design in the griefs / which make us all." The mood is quiet, shaken, and bleakly honest. The poem offers no comfort, only the recognition that death arrives by chance and ties us together.