Degree Of Metaphoricity

Halliday & Matthiessen (1999: 256-7):

… metaphoricity is a relative matter. We can take a pair of agnate expressions and order them with respect to each other, showing that one of the two is more congruent But if we are rewording in either direction — 'packing' or 'unpacking', to use the (lexical) metaphor that was adopted for this by the students to whom it was originally presented —, there is no clearly definable point where we say 'now we have reached the end'. Obviously we cannot go on for very long; the actual number of steps taken will in fact be extremely limited. But any sequence that is reasonably complex in its semantic patterning will be likely to show considerable elasticity at both ends of the continuum.