Halliday & Matthiessen (1999: 444):
Here let us just reiterate our view that all of experience is construed as meaning. Language is the primary semiotic system for transforming experience into meaning; and it is the only semiotic system whose meaning base can serve to transform meanings construed in other systems (including perceptual ones) and thus integrate our experience from all its various sources.
It might be objected that this view leaves no room for scientific or metaphysical models — for example, that we do not allow for the possibility that science has advanced our understanding of the world. This objection would be misplaced: such models are construed in the ideation base as domain models within the overall meaning potential.