Blake uses the image of a dark coffin, saying “Were all of them locked up in coffins of black” (12). In other words, the children are trapped in dark, deathly places, both literally and figuratively. The coffins symbolize where they work, the dark chimneys, and prefigure the fact that working in these chimneys will lead to their death. Although this image is followed by more positive images of the Angel setting the boys free, it shows the harsh reality of their chimney-sweeping situation, conveying the negative message of the poem.
