The poem begins with a bitterly ironic tribute. The speaker praises a forest for its "noble sacrifice" in a battle with the saw, then suggests the only fitting memorial is a field of stumps. That is a strange reward, since the stumps are the very evidence of the loss. The second image works in a similar way: chalky erasers stand in rows like monuments, "in loving forgetfulness / of the blackboard." A memorial built to remember ends up being about forgetting.
The third image, a stone dropped in water, shows ripples spreading outward like a target, and the poem turns them into "spreading years." Time moves away from the moment of loss, and the center fades. The final lines are quietly sharp: "how well we know them then / these unknown dead." The speaker seems to feel a mix of irony and sorrow, suggesting that we claim closeness with the dead while knowing almost nothing about them. The mood is dry, reflective, and a little haunted.