What idea of death does Wordsworth convey in the poem "We Are Seven"?

In "We are Seven," Wordsworth uses the perceptions of an innocent young girl to convey an idea that the death of the physical body is not the end of a person's existence.
The speaker runs into an eight-year old girl with a wild, rustic air about her. He asks her how many brothers and sisters she has, and she explains to him that there are seven in her family. She includes in that number two that have gone to sea and two that are buried in the churchyard.
The speaker argues that if two are dead, there are only five siblings in the family. But the little girl will have none of that. The speaker insists that the two dead children are in heaven, but the girl talks of visiting their graves where she sews, knits, eats her supper, and plays with her brother John. The dead children are as much a part of her life as if they were alive. Death to her is not the end, just part of a larger continuum.