Of course, with so many of Blake's poems, in this selection needs to be balanced against the partner poem that he writes. However, in this poem, we are presented with a young chimney sweeper who weeps in the snow whilst his parents are at church. He says they made him a sweep because he was happy, and now, because he still appears happy, they think they have not hurt him. They system of church and government, he says, rationalises his misery and creates a heaven for the ruling classes out of the misery of the poor.
Note how this poem completely undercuts the naive and innocent hope in God and heaven and a reward for all those who "do their duty" in "The Chimney Sweeper" from Songs of Innocence. This poem clearly identifies the structural nature of poverty with its last line that recognises how the structures of society "make a heaven of our misery." You might also want to think about the stark images that the chimney sweeper uses to describe his plight: his parents clothed him in "clothes of death" and taught him to sing "the notes of woe" as they enslave him to a terrible profession which exploits him and makes him worse than a slave.