What is the defining thematic convention of a 'pastoral elegy' within the lyric genre?

Correct answer: Mourning the dead by casting poet and deceased as shepherds in an idealized landscape

The pastoral elegy is a specialized lyric subgenre that adapts the traditional mourning poem to an stylized rural setting derived from classical Arcadian poetry. It utilizes stock conventions, such as portraying the poet and the deceased friend as shepherds, invoking nature to weep for the loss, incorporating a procession of mourners, and concluding with a sudden pivot toward spiritual rebirth or immortality, as exemplified by John Milton's 'Lycidas' and Percy Bysshe Shelley's 'Adonais'.