In this very short poem consisting of only 9 lines, the speaker begins by declaring that he is moved by nature, and especially by nature's beauty: "My heart leaps up when I behold / A Rainbow in the sky." He goes on to say that he has always felt the impact of nature, even when he was an infant: "So was it when my life began; / So is it now I am a man." The speaker is so certain of his connection with nature that he says it will be constant until he becomes an old man, or else he would rather die: "So be it when I shall grow old, / Or let me die!" In the next line he declares that children are superior to men because of their proximity to nature: "The Child is father of the Man." For this reason, he wishes to bind himself to his childhood self: "And I could wish my days to be / Bound each to each by natural piety."
Written on March 26, 1802 and published in 1807 as an epigraph to "Ode: Intimations of Immortality," this poem addresses the same themes found in "Tintern Abbey" and "Ode; Intimations of Immortality," albeit in a much more concise way. The speaker explains his connection to nature, stating that it has been strong throughout his life. He even goes so far as to say that if he ever loses his connection he would prefer to die.
The seventh line of the poem is the key line: "The Child is father of the Man." This line is often quoted because of its ability to express a complicated idea in so few words. The speaker believes (as explained in more detail in "Tintern Abbey") that children are closer to heaven and God, and through God, nature, because they have recently come from the arms of God. The speaker understands the importance of staying connected to one's own childhood, stating: "I could wish my days to be / Bound each to each by natural piety."
Wordsworth chooses the word "piety" to express the bond he wishes to attain (and maintain) with his childhood self, because it best emphasizes the importance of the bond. His readers would have been accustomed to the idea of piety in the religious sense, and would thus have been able to translate the meaning behind the word to an understanding of the power of the bond Wordsworth hopes to attain.
The format of "My heart leaps up when I behold" gives the poem a somewhat staccato feeling and forces the reader to pause at important points in the poem. For instance, the two short lines of the poem are both quite significant. First, "A rainbow in the sky" harkens back to God's promise to Noah signifying their bond, and foreshadows the speaker's wish to be "Bound...by natural piety." The sixth line, "Or let me die!" shows the strength of the speaker's convictions.