A corpus-based study of grammatical post-metaphorical expressions

In Systemic Functional Linguistics, meanings in semantic stratum could be realized by congruent/premetaphorical, metaphorical, or demetaphorical/post-metaphorical expressions in lexico-grammatical stratum. This paper, evidenced from the Corpus of Historical American English (COHA), explores the specific pathway from metaphorical expressions to post-metaphorical ones guided by principles of Context-first and AS IF and the principle of double functionality. The findings show that grammatical postmetaphorization is mainly realized by post-metaphor of ideation and that of modality. The former finds its expressions from common nouns to proper nouns (e.g. from security to Security), or from uncountable nouns to countable nouns (e.g. from security to securities), and the latter is evidenced by expressions shifting from explicit objective orientation to its explicit subjective counterpart (e.g. from it is possible that to it might be possible that), or by modal probability of I think type shifting from clausal initial position to clausal medial or final position (e.g. I think in the medial or final position of the clause).