What point is the speaker making about elaborate tombs in "Elegy Written in a Country Churchyard"?

In Gray's Elegy, the tomb contains the decorated urns and busts of a once great family, a dynasty now forgotten despite the archealogical ornaments of their honor and vanity. The family, rich in life, is made poor because there is no one to find or appreciate its riches. Gray speculates that the tomb could have contained a "heart once pregnant with celestial fire," just as the famil might have had in life.