Tell me, thou soul
Direct address
The poem speaks to the dead woman's soul, not about it—a rhetorical move that assumes she still exists somewhere. This isn't meditation; it's interrogation.
Location anxiety
Two competing afterlife models: Christian heaven ('delightful world above') versus a classical wandering spirit. Thomson can't decide which cosmology to believe.
Conditional grammar
'Should' and 'if' mark this as hypothesis, not certainty. He's constructing a scenario where grief might be answered, not claiming it will be.