2. A scientific article on the oak thus begins :

"Oak (Quercus), a genus of trees and shrubs of the natural order Cupuliferæ, having monoecious flowers, the male in slender catkins or spikes, the female solitary or clustered; the fruit a nut or acorn, oblong, ovoid, or globular, protruding from a woody cup formed by the enlarged scales of the involucre; the leaves are deciduous or evergreen, alternate, entire, lobed, or sinuate. The species, of which there are about 300, are spread over nearly the whole of the northern hemisphere, except the extreme north. They are more numerous in America than in Europe; a few are found in Asia, none in tropical Africa, in Australia, or in South America except about the Andes."1

Here the information given pertains to any and every oak tree; it must be like this to be an oak. Further, the information pertains not to how the tree looks, but to its essential nature, the notion we are to form as corresponding to the name.

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3. Because the object of exposition is exhibited as conceived and organized in the mind, that is, as a notion, not as an individual, the effectiveness of its presentation depends on mind-qualities, on acumen, clear thinking, breadth. logical notion is a human creation, not an object of nature. By this it is not meant to imply that generalization is a conventional or arbitrary process. The qualities and resemblances from which it is made up really exist, and it is an authentic interpretation of what is in the nature of things. But the detecting of these, and the grouping or separating by vital traits, is the work of a scientifically trained mind, requiring ideally the patience and judicial temper of science.

NOTE. Not less truly in exposition than in description, "the eye sees only what it brings with it the power of seeing"; but while in the described object there is something outstanding to strike on the sight, in the expounded object the power behind the sight must go forth to discover, and virtually to create, its concept. It is mind smiting itself into nature, and on its own plans reconstructing nature.

As exposition, though dealing with real objects, is so largely a matter of terms and logical distinctions, it takes

1 Chambers's Cyclopædia, s.v.

two very different aspects, according as the things themselves or the terms which represent them are in mind. This primal

distinction between notions and names furnishes the basis on which the present chapter is divided.

I. EXPOSITION OF THINGS.

A logical notion, though created and ordered by the mind, has its basis in the nature of things; it is a reality to be interpreted independently of the symbols or terms which name it. The interpretation of symbols, to be considered later, is an affair of language and literary criticism; the exposition of things, though it has to use language as a terminology, is an affair of intrinsic analysis and classification.

Two directions there are in which the exposition of things may be carried. They may be exhibited intensively, that is, in the direction of their depth; or extensively, that is, in the direction of their breadth. In the first case they are treated as species in a class; the business of the exposition being to exhibit the specific traits common to all the individuals. In the second case they are treated as a whole class; the business of the exposition being to assemble and name the various species that together make up the class. These processes, it will be observed, are opposite, or rather complementary, to each other. The general term to denote the first is definition; to denote the second, division.

NOTE. The relation of the terms genus, species, and individual should here be noted. They make a logical series, the species being intermediate between the genus and the individual. With the genus, or class, exposition by division deals; and the traits it assembles, because they apply to the whole class, are called general. With the species exposition by definition deals; and the traits it names, because they are confined to the species, are called specific; in like manner an individual used to exemplify specific traits is called a specimen. As for the individual, and its traits or acts, not exposition but description deals with those; see above, pp. 477, 2, and 555, 2.

I.

Exposition Intensive; Definition. Adopting the broad meaning suggested in the derivation of the word, we may say that to define a thing is to determine its limits or bounds (fines), to exhibit the characteristics that set it off from other things. Whatever goes to determine in language the limits of an idea, whether it be strict logical definition or the literary amplifications and similitudes that serve to make those limits clear to unscientific minds, belongs in the large sense to the definition of the idea.

An object so defined is viewed as one of a class, not as a class in itself; the qualities sought by the definition, therefore, are such as distinguish it from all others in the class assumed for it.

EXAMPLE. If, for instance, our endeavor is to define an animal, we think of the broad class of, say, material things; in which case we have vegetables and minerals in the same class to compare it with and to distinguish it from. Whatever we take as a defining quality must not belong to these. At the same time our defining quality must belong to all animals, must be deep enough to characterize alike an elephant, a human being, an eagle, a crawfish, it takes no account of classes inside its term. If we find the qualities to be life, organism, sensation, voluntary motion, these traits have presumably been tested with reference to the other species of the class, and found not to belong to minerals and vegetables. Two of the qualities, indeed, life and organism, an animal shares with a vegetable, but the mineral does not have them; and when it comes to sensation and voluntary motion, the vegetable in turn is excluded, leaving these as the specific qualities of the animal. Thus, as related to each other species of the class, the animal maintains its separateness. Some such process of comparison and exclusion as this, more or less comprehensive, obtains in the making of every definition.

In the effort to make this kind of exposition complete, and especially to give it literary acceptability, several stages or processes of defining have here to be noted.

1. The Core of Definition.

With the broad range of definition in mind, this is the term by which we may designate its inner mould, what is otherwise called logical definition. By this is meant a concise statement of the trait or traits most essential to an object. In its strict construction it is reducible to two processes. First, the object to be defined is identified with a class of objects. Secondly, its particular place in the class is determined by some distinguishing trait or traits. Another name for logical definition is, definition by genus and differentia, these Latin terms denoting what is determined, respectively, in these two stages of the state

ment.

EXAMPLES. The common definition of mathematics as "the science of quantity" represents each of these stages by a single word. Its class or genus, "science," ranks it alongside of biology, physics, and the numerous other sciences; its species, "quantity," differentiates it from all other sciences by giving it a field all its own.

Some other accepted definitions may here be tabulated by genus and differentia.

Such are strict logical definitions; but also under the more extended and literary definitions may generally be found a recognition of genus and species, each of which is carefully determined. Take for example the following:

which never wholly forsakes every sound politician, of whatever party.”1

Here the genus is determined not by a single term, but by a cumulative employment of related terms 2; while the successive terms of the differentia are chosen according to their fitness to the genus.

Of a logical definition there are four necessary requisites: 1. It should cover all cases or individuals of the idea defined.

2. It should exclude all objects not bearing the same name. 3. It should not introduce for defining purposes the name of the thing to be defined, or any direct derivation of it.

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NOTE. This crude use of names in definition has sometimes been shown up humorously; as when an archdeacon was defined by Punch as a man who performs archdiaconal functions." Shakespeare thus makes Bardolph define accommodated: "Accommodated: that is, when a man is, as they say, accommodated; or when a man is, being, whereby a' may be thought to be accommodated; which is an excellent thing.”

4. It should be expressed in terms simpler and more familiar than the term that designates the defined object. This applies also to a definition for scientific distinction, which, though employing technical terms, is essentially a simplification in the vocabulary of that science.

NOTE. The definition of Oak, on p. 556, above, exemplifies the scientific manner of defining in technical terms.

1 PAYNE, Burke, Select Works, Vol. i, Introd., p. xi.

2 See under Finding the Right Shade of Meaning, p. 47, above.

8"A complete definition distinguishes the thing defined from everything else; it denotes, as you know, 'the species, the whole species, and nothing but the species." " STEDMAN, The Nature and Elements of Poetry, p. 20. 4 King Henry IV, Act iii, Scene 2.