Halliday & Matthiessen (1999: 128):
… a figure is a basic fragment of experience that embodies one quantum of change. As such, it is like a little drama — it is a constellation of actors and props; and it unfolds through time. We can recognise here two complementary perspectives on a figure: composition, and time.Compositionally, figures are phenomenal units that are formed by configurations of other phenomena (elements). Being "units" means that they are constituted as organic wholes with functionally distinct parts. In this respect they differ from sequences, which are not compositional units but loci of serial expansion and projection.Concomitantly, figures take place in time; but the temporal aspect of a figure is typically construed in association with one particular element, the process. We shall therefore deal with this aspect of figures under the heading of process, in the context of our discussion of elements. For the remainder of this chapter we concentrate on the compositional aspect of figures.