In the poem "My Heart Leaps Up When I Behold" by William Wordsworth, the speaker professes an intimacy with nature that is so profound that he becomes awakened and invigorated when he sees a manifestation of nature such as a rainbow. The rainbow in this case, which is commonly associated with beauty, symbolizes all the wondrous aspects of nature.

The speaker's reaction may be extreme, but to him it is essential. As he explains, he has felt this way since he has been a child, and has continued to have such respect and reverence for nature as he has grown up. He hopes to retain this sense of wonder as he grows old. In fact, he makes the extreme statement that he would rather die than lose the feelings he has for nature.

When the speaker states that "the child is father of the man," he is saying that he has a lot to learn from his childhood, when his heart would leap up spontaneously when he was confronted with manifestations of natural beauty. This wonder and excitement is something that should be passed on from childhood to adulthood.

Finally, the speaker hopes that his days will "be bound each to each by natural piety." The word piety implies devoutness, as in religion. The speaker is saying that his devotion to natural beauty is so great that seeing a rainbow or some other beautiful manifestation of nature is like a spiritual experience for him.