Pastoral Poetry
Pastoral poetry is a conventional genre; that is, it has a series of "conventions" or traditions that are normally followed as part of the writing of a poem in that genre.
The history of pastoral can be traced back to the Greek poet Theocritus and the Latin poet Virgil. Both wrote of an idealized, simplified pastoral world that was populated by shepherds and sheep that lived in purer, simpler Golden Age. Pastoral lent itself to allegory, since the connection between the shepherd and the pastor/minister is so clearly appropriate. Indeed, the Psalms use pastoral imagery consistently, and the idea of Christ as the Good Shepherd was as common in Milton's time as it is in our own. Classical pastoral did not, of course, make that connection.
William Empson, a 20th century critic and author of the book Some Versions of Pastoral, emphasizes the pastoral as a way of "putting the complex into the simple"-using seemingly simple people or settings to express complex ideas.
The Pastoral Elegy is a subset of the Pastoral. It uses conventional pastoral imagery in the process of expressing grief over a death. The conventional elements of the Pastoral Elegy are described in the Holman Handbook to Literature: "the invocation of the muse, an expression of the grief felt in the loss of a friend, a procession of mourners, a digression, and finally a consolation [or elegiac reversal] in which the poet submits to the inevitable and declares that everything has turned out for the best, usually through a strengthened belief in immortality" (Holman 382).
Some links on Pastoral:
The Cambridge History of English and American Literature in 18 Volumes
(1907–21). Volume VI. The Drama to 1642, Part Two. XIII: Masque and
Pastoral.
http://www.bartleby.com/216/1312.html
Virgil's Eclogues (look particularly at #4, known as the "Messianic
Eclogue" because it seems to speak of the birth of Christ
http://classics.mit.edu/Virgil/eclogue.html
The Project Gutenberg EBook of Theocritus, Bion and Moschus by Andrew Lang
http://ibiblio.org/gutenberg/etext03/thbm10h.htm
Bibliography:
Holman, C. Hugh. A Handbook to Literature. 3rd Ed. New York: Odyssey Press, 1972.