Get out the microscope, because we’re going through this poem line-by-line.
Perhaps in this neglected spot is laid
Some heart once pregnant with celestial fire;
Hands, that the rod of empire might have sway'd,
Or wak'd to ecstasy the living lyre.
- Now the speaker is reflecting on what type of person might be lying in the unmarked graves in the churchyard
- Maybe, in the churchyard, there lies a person whose heart was once full ("pregnant" means full, here) of what the speaker calls "celestial fire."
- Huh. What could that mean? Sounds like a metaphor to us, since no one's heart is literally full of fire, celestial or otherwise. "Celestial fire" must be a metaphor for passion.
- Maybe, in the churchyard, there lies a person whose hands could have ruled an empire. Or someone whose hands could have played a lyre (a kind of old-school harp) so well that the lyre would have become conscious. That's playing a mean lyre!