In Blake's time, it was common practice in London to use small boys for cleaning chimneys, which was dangerous and often fatal work.
What difference is there in the word choice and tone of these poems from Songs of Innocence and Songs of Experience and in the ideas they convey?
Profoundly affective, "The Chimney Sweeper" from Songs of Innocence is much more subtle and ironic in tone than the one from Songs of Experience, which is vituperative in tone and explicit in meaning. In both the Innocence and the Experience poems, society's consideration of commercial gain above moral values is thematic, but it is expressed differently. In the Experience poem, for instance, the little chimney sweep himself narrates, explicitly telling of his abandonment,
Because I was happy upon the heath,
And smiled among the winter's snow,
They clothed me in the clothes of death,
And taught me to sing the notes of woe.
Then, he indicts society with a bitter tone,
They think they have done me no injury,
And are gone to praise God and his Priest and King,
Who make up a heaven of our misery.
However, the treatment of the Innocence poem is much more implicit with its symbolism, and insinuating in its irony. With the symbols of the bags of soot as the debilitating burden of the little sweeper's life, the soot as the corrupt commercialism of society, and the coffins as representative of the chimneys, disturbing images are created that suggest the theme of the poem; furthermore, the ironic understatement of the last line, "So if all do their duty they need not fear harm," leaves the reader with what T. S. Eliot called "the unpleasantness of great poetry" that is characteristic of William Blake.