The theory of oral-formulaic composition originated in the scholarly study of epic poetry, being developed in the second quarter of the twentieth century. It seeks to explain two related issues:
- the process which enables oral poets to improvise poetry; and
- why orally improvised poetry has the characteristics it does.
The key idea of the theory is poets have a store of formulas (a formula being 'an expression that is regularly used, under the same metrical conditions, to express a particular essential idea') and that by linking these in conventionalised ways, they can rapidly compose verse.
In the hands of Milman Parry and Albert Lord, this approach transformed the study of ancient and medieval poetry, and oral poetry generally. The main exponent and developer of their approaches was John Miles Foley.
 Homeric verse as a source of examples
In Homeric verse, a phrase like eos rhododaktylos ("rosy fingered dawn") or oinops pontos ("winedark sea") occupies a certain metrical pattern that fits, in modular fashion, into the six-colon Greek hexameter, and aids the aoidos or bard in extempore composition. Moreover, phrases of this type would be subject to internal substitutions and adaptations, permitting flexibility in response to narrative and grammatical needs: podas okus axilleus ("swift footed Achilles") is metrically equivalent to koruthaiolos ektor ("glancing-helmed Hector"). Formulae could also be combined into type-scenes, longer, conventionalised depictions of generic actions in epic, such as the steps taken to arm oneself or to prepare a ship for sea.
 The work of Parry and successors
Oral-formulaic theory was originally developed, principally by Milman Parry in the 1920s, to explain how the Homeric epics could have been passed down through many generations purely through word of mouth, and why formulas appeared in it in the way that they did. His work was influential (see Homeric scholarship#Oral Theory and Homeric Question). The locus classicus for oral-formulaic poetry, however, was established by the work of Parry and his student Albert Lord on the Serbian oral epic poetry of what was at the time part of Yugoslavia, where oral-formulaic composition could be observed and recorded ethnographically. Formulaic variation is apparent, for example, in the lines
- a besjedi od Orasca Tale ("But spoke of Orashatz Tale")
- a besjedi Mujagin Halile ("But spoke Mujo's Halil").
- Hrothgar mathelode helm Scildinga ("Hrothgar spoke, protector of the Scildings")
- Beowulf mathelode bearn Ecgtheowes ("Beowulf spoke, son of Ecgtheow")
Magoun thought that formulaic poetry was necessarily oral in origin. This sparked a major and ongoing debate over the extent to which Old English Poetry—which survives only in written form—should be seen as, in some sense, oral poetry.
 See also
- Milman Parry, L’epithèt traditionnelle dans Homère (Paris, 1928), p. 16; cf. Albert B. Lord, The singer of tales (Cambridge: Harvard University Press, 1960), p. 4
 Further reading
- Foley, John Miles (ed. and trans.), An eEdition of The Wedding of Mustajbey’s Son Bećirbey as performed by Halil Bajgorić (2005), http://oraltradition.org/zbm.
- Lord, Albert B. The Singer of Tales. Cambridge: Harvard University Press, 1960 (there is also a second edition, edited by Stephen Mitchell and Gregory Nagy, Harvard Studies in Comparative Literature 24. Cambridge, MA: Harvard University Press, 2000).
- Magoun, Francis P., Jr. “Oral-Formulaic Character of Anglo-Saxon Narrative Poetry”, Speculum, 28 (1953): 446–67.
- Parry, Milman. "Studies in the Epic Technique of Oral Verse-Making. I: Homer and Homeric Style." Harvard Studies in Classical Philology Vol. 41 (1930), 73–143.
- Parry, Milman. "Studies in the Epic Technique of Oral Verse-Making. II: The Homeric Language as the Language of an Oral Poetry." Harvard Studies in Classical Philology Vol. 43 (1932), 1–50.
- Parry, Milman; Parry, Adam (editor) (1971), The making of Homeric verse. The collected papers of Milman Parry, Oxford: Clarendon Press