Halliday & Matthiessen (1999: 573-4):
… we can interpret folk models and scientific ones as co-existing varieties of the same basic system within the ideation base. In the first instance, we will, of course, be aware of them as differing in particular domains — eg as operating with different lexical semantic organisations; but they also tend to construe experience differently in general terms — scientific models tend to rely on grammatical metaphor and thus embody a metaphorical construal of experience …