This piece is comprised of one stanza of nineteen lines--an unusual length for Wordsworth. The rhyme scheme is a complex ababccddefgfghhiijj. The ninth line does not rhyme with any other, and, as we have seen in some of his other poems, Wordsworth uses apostrophe here, deliberately setting the line apart for emphasis.
The theme is also one that we have seen many times in Wordsworth's poetry--that the magic of life disappears as we reach adulthood. The loss of one's exuberant sense of wonder at the natural world starts early, as "Shades of the prison-house begin to close / Upon the growing boy"--a foreboding pair of lines if ever there were any. Here again, Wordsworth urges his readers to resist this jading process, to capture as much of that youthful perspective as possible, and to hold on to it.