Peter H. Fries
In recent years, a number of linguists have been interested in the flow of information in texts. 1 I have been using a systemic-functional approach to discourse analysis to demonstrate the usefulness of the concept of Theme. As a part of that endeavour, it is necessary to develop a better description of Theme. Halliday has defined Theme in the following terms.
The English clause consists of a ‘theme’ and a ‘rheme’…[the theme] is, as it were, the peg on which the message is hung, … The theme of the clause is the element which, in English, is put in first position;…
The Theme is a function of the CLAUSE AS MESSAGE. It is what the message is concerned with: the point of departure for what the speaker is going to say.
It is useful to notice that ‘pegs’ and ‘points of departure’ are semantic notions. The statement that Theme occurs in first position in English is a realizational statement for English, not a definition of the notion of Theme. Further, the definitions quoted here describe Theme as an element of structure of the clause, although elsewhere Halliday makes it clear that he believes other structures, such as clause complexes (1985:56-9) and nominal and verbal groups (1977:183; 1985:158, 166, 176), also have Thematic structures. Following Halliday’s suggestion, I have found it useful to treat Thematic structures in independent conjoinable clause complexes. This structure consists of an independent clause together with all hypotactically related clauses which are dependent on it. The independent conjoinable clause complex is very similar to the T-unit of American educational literature (see Hunt 1965), and so I will use the term ‘T-Unit’, since it is so much shorter.
In Fries (forthcoming a), I have also rephrased Halliday’s definition of the meaning of Theme somewhat less metaphorically in the following terms: