In common with all child chimney-sweepers, Tom leads a pretty hard, miserable life. Forced to toil long hard hours each day in filthy, dangerous conditions for an absolute pittance, it's fair to say that he doesn't have much to look forward to in life. Blake was pretty scathing about the treatment of children in British society, and Tom the chimney-sweep is just one more tragic example of a society that treats its most vulnerable members with indifference and contempt.

And yet, despite his habitual ill-treatment, when Tom wakes up in the dark, ready for another day of back-breaking labor, he actually feels happy and warm. This is because the previous night he had a strange dream. In that dream, an angel of the Lord came down and unlocked the coffins in which tens of thousands of young sweepers had been imprisoned, releasing from their horrific confinement. Happy and free, the boys ran down to the river to wash and play in the water.

As for Tom, the angel told him that if he'd be a good boy he'd have God for a father and never want joy. This is a very happy ending to a very happy dream, and so Tom can be forgiven for feeling happy when he goes to work with the other chimney-sweeps in the cold, pitch-black morning.