The adult language has built up semantic structures which enable us to ʻthink aboutʼ our experience – that is, to interpret it constructively – because they are plausible; they make sense and we can act on them. And the systems of meanings have in their turn engendered lexicogrammatical structures that are likewise plausible: hence we have verbs and nouns, to match the analysis of experience into processes and participants [...] This is how children are able to construe a grammar: because they can make a link between the categories of the grammar and the reality that is around them and inside their heads. They can see the sense that lies behind the code.
- Halliday (1985), a pag.XVIII