William Blake's "The Chimney Sweeper" has an irony to its tone that disguises his revolutionary fervor. For instance, in one part of this poem, there is an exuberant tone as the dream of the boy is described and the lines lightly rhyme,
And by came an angel who had a bright key,
And he opened the coffins and set them all free;
Then down a green plain leaping, laughing, they run,
And wash in a river, and shine in the sun.
This exuberance develops into a more wistful tone:
And the angel told Tom, if he'd be a good boy,
He'd have God for his father, and never want joy.
However, with these lines, there is subtle suggestion of irony.This irony of Blake involves some absurdities that cease to be absurd when understood by the reader. For instance, the boys are, in reality, "locked in coffins of black" as they clean the dark, sooty chimneys "in clothes of death." And, then an angel with "a bright key,"opens the coffins and set the boys "all free," meaning, of course, that the children have died and their souls are then released. And, so, Blake disguises his rage at the inhuman treatment dealt to the innocent children.
Though the morning was cold, Tom was happy and warm;
So if all do their duty they need not fear harm.
While the last two lines appear to rhyme, they oppose each other in connotation, thus underlining the irony of Blake's real message that is disguised with the wistful, exiciting, and peaceful tones.