The title, "August Sixth," hints at a specific day, and the strange glowing cloud in the opening lines suggests the poem may be about a catastrophe. The poem never says so outright, though, so that reading is an inference. What it does show clearly is aftermath: nights are darker, days are "delicate as bones," and the speaker is worn down by guilt and memory. "Blood I have shed" turns to powder, and the speaker claims to have "murdered terror" so that it sleeps.
The speaker's grief spreads outward. Everyone they have known blurs into one man waiting on a corner for a face he loves, and a lonely god cries his name to no one. Even divine promises are "quickly lost." The mood is hushed, mournful, and numb. By the end, language has almost run out, and the only word left is "goodbye."