The poet says that his heart is filled with joy whenever he looks at a rainbow. He says he has felt this way about nature ever since he was a child, and claims he still feels the same.
He believes that he will still love the rainbow when he grows old. He says he would rather die than lose his childlike adoration of nature. He states that childhood has a strong effect on a person’s adult personality. At the end of the poem, he expresses his wish that this "natural piety," or reverence for nature, will be present in all the stages of his life ("And I could wish my days to be / Bound each to each by natural piety.").
Writing the poem in simple language makes the themes of the poem clearer and easier to understand. For example, the connection between the idea of "natural piety" at the end of the poem and the childhood mentioned in the first and second paragraphs, is made clearer when we paraphrase the poem.
