Formal education curbs the potential of the child as it takes away from the child its freedom. The child is like a caged bird in school and just like the wings of the caged bird droop, the spirit of the child sags in school which instils in the child a sense of fear. Children, like plants, need to be nurtured and given care, if they are to ripen successfully and bear fruit later on. If children are not allowed to have a natural childhood, which is spent in playing freely among the natural things (hills, meadows, lambs, birds, etc.), then they will wither before they can blossom into mature adults. Spring stands for new growth and that is why the poet uses the metaphor of the spring to argue that a school does not allow spring to flourish.
