the fourth stanza
The speaker questions his reader, demanding an answer to a rhetorical question.
He asks how a “bird that is born for joy,” referring to himself or others, be asked to “Sit in a cage and sing?”
He knows that he was made to learn, read, and write, but he cannot do so in school, a place he considers equal to a cage.
He makes the case for all children trapped indoors. He professes to worry for their wellbeing and the fact that while they are inside, their “tender” wings drooping, they are forgetting the “spring” of their youth. These children, just like he is, are missing out on the joys of being a child.