CHAPTER IX

EXPOSITION

85. Definition. - Exposition is that kind of discourse wherein the aim is to make clear the meaning of something. It is, in fact, nothing more nor less than explanation. Whenever we set forth the meaning of a law, principle, or general notion, or show how one thing, or set of things, is related to another, we make use of exposition. Broadly speaking, it is the kind of discourse we use when we wish to communicate knowledge. Its appeal is, accordingly, almost always to the understanding alone.

In general, its method may be illustrated by the following:

There is a general harmony in nature between the colors of an animal and those of its habitation. Arctic animals are white, desert animals are sand-colored; dwellers among leaves and grass are green; nocturnal animals are dusky. These colors are not universal, but are very general, and are seldom reversed. Going on a little further, we find birds, reptiles, and insects, so tinted and mottled as exactly to match the rock, or bark, or leaf, or flower they are accustomed to rest upon - and thereby effectually concealed. Another step in advance, and we have insects which are formed as well as colored so as exactly to resemble particular leaves or sticks, or mossy twigs, or flowers; and in these cases very peculiar habits and instincts come into

play to aid in the deception and render the concealment more complete. We now enter upon a new phase of the phenomena, and come to creatures whose colors neither conceal them nor make them like vegetable or mineral substances; on the contrary, they are conspicuous enough, but they completely resemble some other creature of a quite different group, while they differ much in outward appearance from those with which all essential parts of their organization show them to be really closely allied. They appear like actors or masqueraders dressed up and painted for amusement, or like swindlers endeavoring to pass themselves off for well-known and respectable members of society. What is the meaning of this strange travesty? Does nature descend to imposture or masquerade? We answer, she does not. Her principles are too severe. There is a use in every detail of her handiwork. The resemblance of one animal to another is of exactly the same essential nature as the resemblance to a leaf, or to bark, or to desert sand, and answers exactly the same purpose. In the one case the enemy will not attack the leaf or the bark, and so the disguise is a safeguard; in the other case it is found that for various reasons the creature resembled is passed over, and not attacked by the usual enemies of its order, and thus the creature that resembles it has an equally effectual safeguard. We are plainly shown that the disguise is of the same nature in the two cases, by the occurrence in the same group of one species resembling a vegetable substance, while another resembles a living animal of another group; and we know that the creatures resembled possess an immunity from attack, by their being always very abundant, by their being conspicuous and not concealing themselves, and by their having generally no visible means of escape from their enemies; while, at the same time, the particular quality that makes them disliked is often very clear, such as a nasty taste or an indigestible hardness. Further examination reveals the fact that, in several cases of both kinds of disguise, it is

the female only that is thus disguised; and as it can be shown that the female needs protection much more than the male, and that her preservation for a much longer period is absolutely necessary for the continuation of the race, we have an additional indication that the resemblance is in all cases subservient to a great purpose the preservation of the species.1

86. Relation to other forms of discourse. As we have seen, exposition relates itself very closely to certain kinds of description. No hard and fast line, indeed, can be drawn between the two forms. Popular speech, moreover, tends to confuse them. One may "describe" or "explain" the structure of a house, the working of a machine, the plan of a campaign, and so on; and for all practical purposes it matters little whether one chooses to call the result description or exposition. The principles involved in the actual writing are the same in either case. Nevertheless, there is a broad distinction between the two forms. Description deals properly with the individual, the particular; exposition, on the other hand, concerns itself solely with the general.

A like closeness of relation between exposition and argumentation is also to be noted. Exposition, indeed, forms, as it were, the very groundwork of argumentation, for the first step in convincing a man. of the truth of a proposition is to make him understand it. Moreover, exposition is often used for an argumentative purpose, as, for instance, when one

1 A. R. Wallace, Natural Selection.

explains a principle or theory with the idea of getting some one else to accept it as a truth. In this case more or less of an argumentative tone will doubtless be given to the explanation so as to make the purpose evident. In fact, one would probably be safe in saying that most argumentative discourses are made up in this way exposition with a thread of persuasion running through it. Notable examples of such a blending of the two forms are Darwin's Origin of Species and Huxley's Three Lectures on Evolution.

Pure exposition, however, is dispassionate. There is in it no desire to influence the reader this way or that. Its sole end and aim is to set forth the truth.

87. Kinds of exposition. In pure exposition the main business of the writer is the determining of the meaning or scope of general ideas or notions. With the peculiarities of individual things, considered as individuals, exposition, as we have seen, has nothing to do; that forms the province of description. Exposition takes account of things only as they are grouped together in virtue of the possession of common attributes or qualities. That is to say, it deals with things brought within the compass of a general notion, things to which a general term may be applied.

Broadly speaking, the exposition of a general idea may take one or other of two forms, which, from the central purpose in each, we may call exposition by definition and exposition by classification. Thus in expounding the idea of a vertebrate, let us say, a

writer may either try to make clear what a vertebrate essentially is, that is, what are the characteristics possessed by all vertebrates in common, or he may try to show how all the individuals to which the term "vertebrate" may be applied may be grouped or arranged in classes so as to bring out their relationship to one another. His exposition in the first place would be definition; in the second place, classification. The two forms are not, of course, always kept distinct; but usually the main purpose of any expository discourse is either definition or classification.

88. Exposition by definition. - Exposition by definition is the determining of the meaning or content of a general idea, the setting forth of the essential characteristics or attributes of the things thought of as included in the idea. Its aim is to bound or limit the idea so that it may become distinct from all other ideas. Hence it should set forth clearly and in detail as many of the distinguishing characteristics of the thing defined as possible.

Note with what elaborate completeness Newman. expounds the idea of a gentleman in the following:

Hence it is almost a definition of a gentleman to say he is one who never inflicts pain. This description is both refined and, as far as it goes, accurate. He is mainly occupied in merely removing the obstacles which hinder the free and unembarrassed action of those about him; and he concurs with their movements rather than takes the initiative himself. His benefits may be considered as parallel to what are called comforts or conveniences in arrangements of a personal nature: like an easy-chair or a good fire, which do their part