Halliday & Matthiessen (1999: 537-8):
Under certain historical conditions, such a theory [i.e. the congruent model] may come to be modified or reconstructed. No doubt there have been various more or less catastrophic changes in earlier human history which have brought about relatively rapid changes in language — relatively, that is, to the gradual evolution of the system that has taken place all the time. We have no means of knowing about these. But it seems likely that what we are here calling grammatical metaphor represents one such partial reconstruction, in which, in the context of science and technology, a rather different kind of "reality" is being construed.
Blogger Comments:
Note the much earlier emergence of lexical metaphor, and the rather different kind of "reality" it construed: the rich symbolism of the various mythic traditions.