The speaker begins with a run of impossible tasks: catching radiance as it streams past, prying open a rainbow, setting light into the eyes of a dead squid. The conclusion is a weary one: you know you can't, but you keep trying anyway. Next comes the image of calling "Lazarus!" to raise the dead. The speaker admits that once they might have had a scream strong enough, but not anymore.
From there the poem turns its central image into a freeway where every individual scream joins a slow, endless crawl of other screams. Nobody gets a fast lane, and nobody can hold back the breath that carries a wail out. The speaker imagines the noise rising until it breaks the sound barrier, leaving only an open mouth, like the silent scream in Emil Nolde's oval-mouthed figure. The final lines state the point plainly: all the noise in the world can't cancel out or match the anguish of a single death.
The mood is grief mixed with exhaustion and stubborn persistence.