thing is a plant tells a great deal about it; to say that it weighs less than a pound tells hardly anything.

It is this principle of trying to get into the same class those objects which on the whole are most alike that prevails in the classification of animals and plants in natural history and of books in the subject-catalogues of libraries.

Any system of classification that regards general resemblance is liable to be upset by an advance in knowledge or a change in scientific interests. The common man calls a whale a fish, the zoölogist says it is not a fish but a mammal, because he has found out that on the whole living in the sea and looking like a fish involves fewer other noteworthy characteristics than suckling the young. In Dewey's Library Index illusions are classified with witchcraft and fraud because they involve deception, and for the general reader this is perhaps the best classification; but a psychologist would classify illusions along with ordinary perceptions, because both are interpretations of sensations made in precisely the same way, and he knows that the correctness or incorrectness of the interpretation, which strikes the layman and upon which Dewey's classification depends, is a mere accident and does not involve any further differences in the mental processes. To illustrate the influence of wider knowledge or deeper insight upon a whole system of classification it is only necessary to point out how the old hard and fast lines between genera and species in natural history have been wiped out by the theory of evolution, which shows how new species are being created continually though slowly by the inheritance and consequent accumulation of a vast number of small individual variations.

The fact that a system of classification is likely to be upset by wider knowledge is no reason why it should not be constructed, for a bad classification is better than confusion; and however bad it may be, it is likely to contribute something toward the attainment of the wider knowledge by which it can be corrected.

When a classification has been made, the resemblances and differences which it indicates can be still further marked and more easily remembered and talked about by Naming. the use of class names. The words vertebrate, mammal, radiate, batrachian are all scientific terms invented for this purpose. But the use of class names was not invented by scientists, for every common name marks out a class of things which it serves to distinguish from all others. Animals and plants, trees and grasses, hawks and doves, were distinguished and contrasted long before science existed. The scientist, as Venn says, usually finds the highest and lowest classes of things already made and named. His business is only to state their most important differences distinctly (which sometimes involves a correction in the classification of an ambiguous kind, such as the whale) and to arrange the intermediate groups.

CHAPTER V.

THE USES OF SINGLE WORDS AND PHRASES.

We have seen already how to avoid certain gross blunders which result from the ambiguity or misinterpretation of words and statements; but if we are to acquire any fine discrimination in the interpretation and use of language our study of words and sentences must not end here. Hence several chapters more must be devoted to them.

To understand the exact meaning of a word in any particular sentence it is not enough to know its definition; for however unambiguous the meaning of a word may be as given in a dictionary it may be used for any one of several different purposes, and if we do not understand the differences between these purposes we cannot be sure of interpreting the word aright.

With reference to each one of these different purposes words are divided into different classes-usually two; but since the same word can be classified with reference to different purposes it can belong to as many different classes as there are purposes with reference to which it can be classified. We shall see, however, that not every word can be classified with reference to all these different purposes.

The first division of words which we shall consider is into Terms. those that are Terms', and those that are not. A term is a word or group of words used to indicate or identify the objects about which a person speaks, or the states, qualities, actions or other relations whose possession by

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an object is under consideration. It is, in brief, a name in the broadest sense of the word. In the sentence The present Emperor of Germany is remarkably energetic' the first five words are regarded as a single term because they are used together to point out the individual under discussion; and because the last two words of the sentence are used together to indicate a single quality, they also are regarded as a single term. In other connections, of course, the words Emperor, Germany, energetic, would be regarded as separate terms, e.g., The Emperor is energetic; Germany is a beautiful country. Even in the case of the sentence given, if we should be asked to define our terms' it would be proper enough to take up the words separately, as they might appear elsewhere, and explain that by 'remarkably' was meant, not 'excessively', but noticeably'; by energetic', not meddlesome but vigorous'. But if we wished to be absolutely accurate, though tedious, we should add to our explanation of the meaning of the separate words an explanation of the phrase or term as a whole.

Though every term is a word or combination of words, the structure of language is such that some words can never be used as complete terms. The object of thought is indicated y the subject of a sentence; its relations under discussion, by the predicate. Such words as prepositions, conjunctions and adverbs cannot be either subjects or predicates and therefore they cannot be terms, though they can be parts of terms. We cannot say, for example: Of is energetic; nevertheless is very; etc. We can say of' is a preposition; but then the word is used as a noun and is not taken in its ordinary sense. Unless a relation is discussed-affirmed, denied, or questioned-the word that indicates it is not a term. The word of' in the phrase The Emperor of Germany' indicates a relation, but it is not a term, because nothing is said about the relation it indicates. It merely forms a part of the description of the object some other of whose relations is discussed. Prepositions joining nouns to

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each other, and possessive cases are always devoted to the expression of relations which are involved in the conception of an object but not discussed. For that reason they can never be terms. On the same principle, adjectives are true terms when they follow the verb 'to be' or its equivalents as predicates, e.g., in the sentence The horse is white', but not when they are in their usual position, as in the sentence The white horse kicks'.

Words which can be used as complete terms are called Categorematic (Greek, kaτnyopé∞, to assert); those which can not, and which therefore can not be used except when they are combined into a term with others, are called Syncategorematic (Greek, σuv, together with, and kaτny opé∞). κατηγορέω).

The distinctions which we have to discuss in the rest of this chapter all have reference to terms. We shall therefore have nothing more to say at present about syncategorematic words.

The first distinction to be made with reference to terms is between those which are used demonstratively and those which are used descriptively. By a Demonstrative term is meant one that points out an ob

Demonstrative and

descriptive. ject; by a Descriptive term, one that tells something about it.

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When we say 'John is angry' or 'That is very beautiful', the words 'John' and 'that' are used demonstratively and the remainder of the sentences are intended to describe the objects that they point out. The word John' is of course a proper name and the word 'that' a' demonstrative' pronoun. These parts of speech are devoted so exclusively to pointing objects out, and adjectival phrases like 'angry' and 'very beautiful' are devoted so exclusively to their description that if the order of the sentences. were reversed and we said 'Angry is John' or 'Very beautiful is that', it would still be plain which words were used to point out the objects under discussion, and which were used to describe them.

In the examples just given the subject of each sentence