Halliday & Matthiessen (2014: 63):
As the text unfolds, patterns emerge, some of which acquire added value through resonating with other patterns in the text or in the context of situation. The text itself is an instance; the resonance is possible because behind it lies the potential that informs every choice made by the speaker or writer, and in terms of which these choices are interpreted by listeners and readers. We refer to this ongoing creation of meaning in the unfolding of text as logogenesis.