You will be able to increase both your speed of reading and your comprehension if you can recognise some of the rhetorical functions that the writer is using. Writers use language, for example, to analyse, to describe, to report, to define, to instruct, to classify, to compare, to give examples, to explain, to give reasons, to argue and discuss and to draw conclusions. To understand the text it is necessary to understand what the writer's purpose is.
The following paragraph describes a building:
The largest building, in the very centre of the town, is boarded up completely and leans so far to the right that it seems bound to collapse at any minute. The house is very old. There is about it a curious, cracked look that is very puzzling until you suddenly realize that at one time, and long ago, the right side of the front porch had been painted, and part of the wall - but the painting was left unfinished and one portion of the house is darker and dingier than the other. The building looks completely deserted. Nevertheless, on the second floor there is one window which is not boarded; sometimes in the late afternoon when the heat is at its worst a hand will slowly open the shutter and a face will look down on the town.
The following example classifies, and also describes.
The Classification of Species
The group species is the starting point for classification. Sometimes smaller groups, subspecies, are recognized, but these will not concern us until we discuss evolution. There are many larger groups: genus, family, order, class, phylum, and kingdom. Let us begin with the first seven species. We belong to the genus Homo and to these more inclusive groups: (1) the family Hominidae, which includes, in addition to Homo, extinct men not of the genus Homo, and (2) the order Primates, which includes also the lemurs, monkeys and apes. The three cats - lion, house cat, and tiger - belong to the genus Fells. In general we can think of a genus as a group of closely related species. The three cats also belong to the family Felidae. Generally a family includes related genera. The first seven species, different enough to be put in three orders, are yet alike in many ways. All are covered with hair, they nurse their young with milk, and their red blood cells are without nuclei. Because of these and other resemblances they are combined in a still more inclusive group, Class Mammalia. A class, therefore, is composed of related orders.
The following paragraph pattern is one in which several things are compared or contrasted.
A one-million-fold increase in speed characterizes the development of machine computation over the past thirty years. The increase results from improvements in computer hardware. In the 1940s ENIAC, an early electronic computer, filled a room with its banks of vacuum tubes and miles of wiring. Today one can hold in the hand a computing device costing about $200 that is twenty times faster than ENIAC, has more components and a larger memory, is thousands of times more reliable, costs 1/10,000 the price, and consumes the power of a light bulb rather than that of a locomotive.
In this type of pattern, the purpose is to explain cause and effect.
One of the most important properties of a liquid is that its surface behaves like an elastic covering that is continually trying to decrease its area. A result of this tendency for the surface to contract is the formation of liquids into droplets as spherical as possible considering the constraint of the ever-present gravity force. Surface tension arises because the elastic attractive forces between molecules inside a liquid are symmetrical; molecules situated near the surface are attracted from the inside but not the outside. The surface molecules experience a net inward force; and consequently, moving a surface molecule out of the surface requires energy.
The following paragraphs gives arguments for and against.
One of the first men to make a commercial success of food conservation was Henry John Heinz. He started by bottling horseradish, and he was so successful that in 1869 he founded a company in Pittsburgh, USA. Like other Americans of his generation, Heinz made his name a household word throughout the western world. At last, man seems to have discovered how to preserve food without considerably altering its taste. The tins of food (Heinz tins!) which Captain Scott abandoned in the Antarctic were opened 47 years after his death, and the contents were not only edible, but pleasant.
The main argument against conserved foods is not that the canning of food makes it taste different; rather, people complain that the recipes which the canning chefs dream up are tedious or tasteless when it is eaten in great quantities. And a company like Heinz can only produce something if it is going to be eaten in great quantities. The tomato is very pleasant to eat when it is freshly picked. A regular diet of tomatoes alone could well prove tedious. The canning companies try to cook the tomato in as many ways as possible. The Heinz factories in Britain use millions and millions of tomatoes every year. They claim that if all the tomatoes were loaded on to 15-ton lorries, the line of lorries would stretch for 60 miles.
But there are many people who do not like to eat food out of season. They like their food to be fresh, and they like to cook it themselves in "the old-fashioned way". But it is very difficult for modern man to realise what it is like to live without the advantages of pre-packageded and canned food. European society in its present form could not cope without modern methods of food processing. Imagine your local supermarket without all the cans of pre-packaged foods. There wouldn't be much variety left, and what was left would have to be increased enormously in order to give the same amount of food. The supermarket would turn into a chaos of rotting vegetables, stale bread and unhealthy meat. The health problems would be insurmountable, unless we all went into the country to support ourselves.
So next time you reject canned food as being tasteless or unimaginative, remember that you can only afford to eat fresh food because canned food exists.
The following paragraph is a narrative; it tells a story.
Harold I (of Norway), called The Fairhaired (860?-940?), was king of Norway (885?-933?), and the first person to rule, at least nominally, the entire country. Harold inherited three small domains in eastern, central, and western Norway from his father, Halfdan the Black, and set out to conquer the rest of the country. After many years of campaigning, during which the chieftains of western Norway offered the most stubborn resistance, Harold gained his final victory in the Battle of Hafrsfjord, which probably took place around 885, although it may have been some years later. Once in power, Harold ruled with a strong hand and consolidated his realm. One result of his firm rule was the acceleration of the immigration that had begun shortly before to pioneer settlements in Iceland. Many chieftains also fled to the Western (British) Isles, from where they and their kinsfolk in the Orkneys, Shetlands, and Hebrides raided the Norwegian coast. Harold was finally compelled to send a punitive expedition across the North Sea to flush out these Vikings. For the same purpose he entered into an alliance with King Athelstan of England; but he made no actual conquests. In his old age Harold abdicated in favor of his eldest legitimate son, Eric Bloodaxe, who was deposed by his half brother Håkon I after a few years of misrule.
For more information and examples see Writing: Functions.
Try these exercises: Exercise 1