I came across this memorable quote from Albert Lord’s The Singer of Tales, reading for my seminar tomorrow night:
The method of language is like that of oral poetry, substitution in the framework of the grammar. Without the metrical restrictions of the verse, language substitutes one subject for another in the nominative case, keeping the same verb, or keeping the same noun, it substitutes one verb for another. In studying the patterns and systems of oral narrative verse we are in reality observing the ‘grammar’ of the poetry, a grammar superimposed, as it were, on the grammar of the language concerned. Or, to alter the image, we find a special grammar within the grammar of the language, necessitated by the versification. … The speaker of this language, once he has mastered it, does not move any more mechanically within it than we do in ordinary speech.
When we speak a language, our native language, we do not repeat words and phrases that we have memorised consciously, but the words and sentences emerge from habitual usage. This is true of the singer of tales working in his specialised grammar.