Little Tom Dacre used to have white hair (before it was shaved), the naked children in the dream are white, and clouds are white. Whiteness in this poem is a symbol of innocence and childhood and contrasts with the blackness of soot, chimneys, coffins, and all the other bad things (adulthood, death, etc.) the poem mentions.
- Lines 5-6: Tom's hair used to resemble a lamb's before it was shaved. The speaker compares Tom's hair to a lamb's using a simile, which helps establish the lamb is a symbol of childhood and innocence.
- Line 8: Tom apparently has "white" hair. This could mean he's just a blond, but white is also a symbol of innocence, purity, and childhood. He's not just a blond—he's a young one, who's being spoiled by his awful job.
- Line 17: The children are now white and naked. Finally, all that grimy soot is scrubbed clean from their bodies, and so they appear white. But this whiteness is also a symbol of their innocence, purity, and childhood. In Tom's dream, these kids are free to be just that—kids.
- Line 18: The children rise on clouds, which are usually white. Sounds fun, right?