Internal Complementarity: Metafunctional

Halliday & Matthiessen (1999: 562)

… in the congruent mode of construing experience, there is a metafunctional complementarity: the ideational potential offers two complementary modes for construing experience — the highly generalised logical mode, with projection & expansion as the dominant semantic motifs, and the more particularised experiential mode, with its typology of processes, things, qualities, and circumstances …