Halliday & Matthiessen (1999: 268):
The "secondary motif" is that whereby a 'thing' (congruently construed as a noun functioning as Thing in a nominal group) is metaphorised on the model of some quality — qualifying, possessive or classifying. This represents a shift one step 'backwards' along the logical–experiential scale. It is thus contrary to the prevailing general tendency, since something that is congruently a participant on its own terms is now treated as existing only by virtue of some other participant.This type of shift occurs only in syndromes, where the process is reconstrued as a participant; and as a corollary, the participants in that process become its 'qualities'. For example, Griffith's energy balance approach to strength and fracture, where the participants strength and fracture and energy balance have become 'qualities' expanding the metaphoric 'thing' approach — compare the more congruent Griffith approached strength and fracture in terms of (the concept of) energy balance.