The Chimney Sweeper (Songs of Experience)
How we cite our quotes:
Because I was happy upon the heath
And smiled among the winter's snow (5-6)
The chimney sweeper says he was "happy upon the heath"; a heath is a wide open space, associated with wildness and freedom. So, for this kid, happiness is freedom to frolic. But now that the kid's no longer free, he can't be happy, right?
And because I am happy and dance and sing,
They think they have done me no injury (9-10)
Happiness is here again close to sadness; the chimney sweeper says he sings, but remember, he sings notes of woe. So is he really happy? Or does he just sound happy, if you're not paying attention?
And are gone to praise God and his priest and king,
Who make up a heaven of our misery" (11-12)
The phrase "make up a heaven of our misery" suggests that happiness is often a product of sadness; "God, and his priest and king" can only make themselves a heaven, after all, if they have the child's misery.