The rhyme scheme of "My Heart Leaps Up" by William Wordsworth is ABCCABCDD. In this poem, the speaker describes the joy he feels in nature, as well as his hope that his enjoyment of nature lasts for the rest of his life.
In the first section of the poem, the speaker describes the specific elation he feels when he sees a rainbow, noting that he had the same feelings as a child. He then hopes that this joy lasts until his old age, wishing to die if it does not.
The last three lines of the poem makes a similar point more broadly. It begins with a paradox: "The Child is father of the Man." By this, he speaker means that one's childhood experiences condition one's adulthood. Because he adored nature as a child, he hopes that he will spend all of his adult days in reverence of nature, too.