Theme -rheme is based on functional sentences perspective dealing with how
information is distributed in sentences, and the effect of this distribution in
discoures.
Linguists have used different terms to refer to theme - rheme
including background - focus, given - new, and topic - comment,but Halliday
(1985) enumerates some fundamental distinctions between them and
scrutinizes each category separately. In this paper we follow hallidays model
of theme-rheme organization and try to apply it in some literary and SCIENTIFIC
texts. Theme - rheme has a great importance in terms of socio - linguistics and
psycholinguistics so that any change in the organization of theme - rheme
affects the message and its degree of comprehensibility. Since thematisation is
one of the textual strategies for creating a common world between the
addressor and his addressees we mix up the text without resorting to this
strategy. Weissberg (1984) concludes that comprehensibility and recallability
of text is to some extent a function of the way in which information is
distributed, i.e. in unmarked sense, recall and comprehension is faster and
more accurate. In this research some texts have been analyzed in terms of
seven patterns of theme DEVELOPMENT including linear, constant,
miscellaneous, marked,. multiple, implicit and absent themes presented by
Weissberg.