Flow of information in paragraphs
In order for a paragraph to be easy to read, the information in it must flow easily from one sentence to the next. To do this it is important to structure your information clearly and signal exactly what you want to say by the use of signalling words.
Most sentences in English have two parts a theme (or topic) and a rheme (or comment) (McCarthy, 1991, p. 55). The theme is what you are writing about - it is shared information and it has been introduced to your reader. The rheme is what you are saying about the theme - it is new information, what you want to tell your reader.
Look at the following sentences:
1. The M1 goes from London to Leeds.
2. The motorway from London to Leeds is called the M1.
The theme in sentence 1 is "the M1". The reader has been introduced to the M1 but does not know where it goes and therefore needs to be told. In sentence 2, the theme is "the motorway from London to Leeds". The reader knows there is a motorway from London to Leeds but does not know what it is called.
In English the theme usually comes at the beginning of the sentence and the rheme at the end. The decision about which part of the sentence to make the theme and which part to make the rheme depends on the information that needs to be communicated. This depends on the sentences that come before.
Look at the following short paragraphs:
3. I was born in Glasgow. Glasgow is the largest city in Scotland.
4. I was born in Glasgow. The largest city in Scotland is Glasgow.
All the sentences are grammatically correct but in example 4, the information to be communicated, the rheme - the largest city in Scotland, is at the beginning of the sentence. Example 3 is preferred in English.
There are two basic choices in organising information texts:
1. The rheme of one sentence becomes the theme of the next sentence.
The complete electrical behaviour of any valve or transistor can be described by stating the interrelation of the currents and the voltages between all the electrodes. These relationships can conveniently be displayed graphically, and the various curves are known as the 'characteristics' of the device. In principle, all the characteristics should be available to the designer proposing to use the device in a circuit.
(W. P. Jolly, (1972). Electronics, p. 61)
2. The theme of one sentence is the same as the theme of the next sentence.
Anthropology is the study of humankind, especially of Homo sapiens, the biological species to which we human beings belong. It is the study of how our species evolved from more primitive organisms; it is also the study of how our species developed a mode of communication known as language and a mode of social life known as culture. It is the study of how culture evolved and diversified. And finally, it is the study of how culture, people, and nature interact wherever human beings are found.
(Marvin Harris, (1975), Culture, people nature, p. 1)
NB: A mixture of the two is also possible.