Grammaticalization of complementizers in Old English glosses

I investigate how complementizers, which connect subordinate clauses to the main sentence, develop from other parts of speech, namely prepositions and adverbs. This occurs by the process of grammaticalization, in which a word loses lexicality and gains grammatical function instead. I use computer-based corpus analysis to determine how often certain words are used as each part of speech in my selected texts, and whether they are accompanied by other grammatical words. I use two Old English glosses of the Latin gospels, the Rushworth and Lindisfarne glosses, in order to analyze possible diachronic and geographical differences between the texts. I demonstrate that prepositions develop into adverbs and thence into complementizers with the assistance of certain grammatical accessory words which are later lost. This occurs by the process of reanalysis, in which the language user interprets a word or phrase differently than before.