Delicacy Vs Instantiation

Halliday (2008: 84, 83):

[With] grammar and lexis […] the complementarity is one of focus, based on the scale, or vector, of delicacy. System and text, on the other hand, form a complementarity of angle, based on the vector of instantiation. …

What I am here calling system and text are two complementary positions of the observer, two observational perspectives on the phenomenon — in this case, on the phenomenon of language. Thus "text" is the instantiation of the system; or alternatively, "system" is text potential.