Halliday & Matthiessen (1999: 530):
All languages display some form of textual organisation of the clause. How far this kind of speaker - listener complementarity, with a quantum of information being construed out of the tension between the two, is a general or prototypical feature of this aspect of the grammar is not at all clear.
In Austronesian languages, for example, there is typically a much more complex pattern of interrelationship between the textual and the ideational structures of the clause (mapping of Theme on to different transitivity roles) than is found in Indo-European. Even with regard to English, where it is well established how the flow of information is engendered in the grammar, opinions differ as to how far this should be seen as one continuous movement and how far as the intersection of two different periodicities (as we are inclined to interpret it).
It may be a general principle that thematic status is more closely tied to the clause (as the locus of experiential and interpersonal choices) than is the listener-oriented pattern of given and new; in English the "quantum" of information that is defined by this latter construction is not, in fact, identical with the clause and may be smaller or larger. But all discourse is organised around these two motifs, which between them "add value" to the clause, enabling it to 'mean' effectively in the context in which it occurs.