Halliday (2008: 184):
As I described it, grammar and lexis form a complementarity of focus; system and text form a complementarity of angle; speaking and writing form a complementarity of state. We could gloss these further by identifying the dimension along which they are counterposed.
- Grammar and lexis are opposed in delicacy: meaning as generalities or as particulars.
- System and text are opposed in instantiation: meaning as (collections of) instances or as potential.
- Speaking and writing are opposed in (manner of) realisation: meaning as happening or as thing.
But they all have a critical property in common: they are all strategies for extending the semogenic power of language — its meaning potential as a semiotic system.