What is the essence of the poem?
it is ironic verse that William Blake writes, for while maintaining a non-judgmental tone with the point of view of a child, the poem is a scathing indictment against the exploitation of innocent children by a society that exploits moral platitudes about duty and goodness to promote its own ends. When, for instance, the boy cries about his slavish job and the grime that covers him, the child speaker consoles him,
Hush, Tom! never mind it, for, when your head's bare,
You know that the soot cannot spoil your white hair.
Further, the speaker tells Tom, "If all do their duty, they need not fear harm"; in other words, this rhyming moral, like that of a nursery rhyme, ironically preaches that the boy should do his "duty" and submit to his fate, ignoring the cruelty of such a duty.
In another irony, Blake includes his poem in Songs of Innocence and Experience. For, while childhood is normally a time of innocence, the boys who are chimney sweeps experience the evil of a society which exploits children. In a further irony, the children retain their innocence as they fail to understand the guilt of their society and, despite their tender ages, look forward to a spiritual reward for their obedience in the hereafter.