What is the theme of William Blake's poem "The Chimney Sweeper?"

William Blake wrote two poems with the title "The Chimney Sweeper," and they are very different from each other. One poem is a "Song of Innocence" and is written entirely in first person by a chimney sweeper. In this poem, the sweeper has a positive attitude about having been sold as a chimney sweep when he was very young. He encourages a fellow sweeper, Tom Dacre, who was sad to have his head shaved. He helped him look on the bright side by pointing out how the soot would not be able to spoil his white hair now. After hearing that encouragement, Tom Dacre dreams of several young sweepers who are "lock'd up in coffins of black." In his dream, an angel opened the coffins and freed the boys, who then were able to play in the grass and "wash in a river and shine in the Sun." The theme of this poem is that no matter how dismal one's life is, one can always dream and hope of a pleasant future to come, and one can always find something to be thankful for. 

The second poem, a "Song of Experience," takes a much darker view of the chimney sweep's fate. The poem starts out by asking a little sweeper where his parents are. Lines 4 - 12 are spoken by the sweeper in first person. He states his parents have gone to the church to pray. He explains that since he was a child of a cheery disposition, they sold him to be a chimney sweeper--evidently believing his positive personality could endure the hardship. The sweeper admits he is still happy and dances and sings, which causes his parents to assume "they have done me no injury." He then states that his parents have "gone to praise God & his Priest & King, / Who make up a heaven of our misery." By saying that the parents are "making up" a heaven, the poem suggests not only that the Christian Heaven is a mere fiction, but also that the happiness they imagine their son enjoys is also a fantasy of their own creation, one that helps them justify what they have done to their child for money. The theme of this poem is that people use religion to justify their actions and that just because a person displays outward happiness does not mean that he is happy inside, or that those who have caused him hardship should not be held accountable.

Blake's "Songs of Innocence" and "Songs of Experience" included many paired poems. The former took an innocent, naive view of the world while the latter took a hardened, pessimistic view of the world. Blake believed that "without contraries there is no progression." In other words, looking at two opposing viewpoints can result in progress toward understanding and truth. These contrasting poems with their contrasting themes are meant to help us better understand the issue of childhood hardships.