and with a vague, comfortable feeling that it explains everything, than to stop and discuss for your reader just exactly how much of its meaning you are using for your present purpose. You cannot get along without these general terms; but it is a safe rule always to define them and limit them as specifically as did Darwin.

On the other hand, one should not neglect the fact that such figures of speech, almost more than any other device, make reasoning and explanation possible; they are the only means by which scientific men can record the advance of knowledge. Moreover, this falling back on figures of speech which imply a physical sensation again suggests the analogy between explanation by words and by diagram. The elaborate simile at the end of the second extract which I print from the "Origin of Species," shows the closeness of this analogy, page 198 :

"The affinities of all the beings of the same class have sometimes been represented by a large tree. . . . As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch; so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramifications."

Here is exactly the same thought set out in words which had been set out in the abstract by the diagram which I have already discussed, page 29. In each case the purpose was the same, and the process of explanation differed only in unessentials; for

whether by the diagram or by the simile Darwin had recourse to that curious immediate, almost physical sense of relation which accompanies every thorough understanding of a subject.

Generally, as I have said, the metaphor which sums up a long course of thought will be reduced to a single word or phrase which explains itself. But when the word has been so long used that the sense of its original figurative meaning has been blurred or rubbed out, as in such cases as classical, poetry, democratic, relation, and most of the commonest general words, then the only safe way is carefully to give your own definition. Most people do their thinking in these vague and inexact terms, which express at best not much more than hazy intentions of ideas. Matthew Arnold was the great exemplar of the definition of terms; he, writing criticism, of necessity used many terms like the grand style, culture, high seriousness. Such terms as these, which, as perhaps he did not always perceive, are in the last analysis terms of commendation-statements that you like or do not like a thing—are for purposes of explanation dangerous since they will be understood by different people in different ways and will be taken as applying to various objects. But see the care with which he uses such a phrase; he speaks of the grand style thus 1: —

"The grand style arises in poetry when a noble nature, poetically gifted, treats with simplicity or with severity a

1 Quoted in A. S. Hill's "Principles of Rhetoric," p. 320.

serious subject. I think this definition will be found to cover all instances of the grand style in poetry which present themselves. I think it will be found to exclude all poetry which is not in the grand style. And I think it contains no terms which are obscure, which themselves need defining."

Though it may be questioned whether such terms. as noble, simplicity, severity, always mean the same thing to all minds, it is safe to say that if ever such a term as grand style can be fixed by definition, it is so fixed here. At any rate, Arnold's tests have become noted; and they are of very practical service in writing explanations. If you are using a treacherous general term, ask yourself whether it covers all the specific facts for which you use it, whether it excludes all other facts, and whether in itself it contains terms which can be misunderstood by any rational reader.

In practice use general terms in exposition when they will sum up a long process of thought in a single phrase, and will make your reader see the subject swiftly and immediately; but in using them remember always that they are treacherous; that they carry so many ulterior implications both of thought and feeling, that you yourself may be led astray in using them; and, moreover, that they put you at the mercy of careless readers.

17. The other danger in explanation, of being more abstract than is necessary, and so letting your explanation slip by your readers' minds, is apt to arise

in two ways: in the first place, in the case of the great thinkers whose intellectual powers work, as it were, by leaps and flights; in the other extreme, from people who are too lazy to think their subject out in specific detail. Of the former class metaphysics is full of examples, such as Kant's "Critique of Pure Reason;" such men do not concern us here. The other class, the people who out of mere laziness. write in general abstract terms, are common enough; for it is much easier to write on an abstract subject in the hackneyed general terms which lie ready at every one's service than to make your own generalizations fresh from the facts of your own experience of life. It is only the man who can think clearly who is not afraid to think hard, and to test his thought by the actual facts of experience. It is a great deal easier, for example, to devise an ideal scheme of education in general than it is to sit down and work out a series of courses which will be practicable for the five days of five hours each in grammar and high schools. Moreover, it is to be remembered that the object of all explanation is to satisfy the irrepressible instinct of man to understand his universe; and this universe is made up, not of hazy abstractions, but of hard and concrete. facts. The men who have added to this understanding of the world have been the men who have made it possible to see more of the meaning of the real things of the world: men like Newton, who showed that the sun and the moon and the stars obey the same law as the falling stone; men like Franklin

and his successors in electricity, who have brought together the thunderbolt and the crackling when you rub a cat's back; men like Tyndall, who have made it a matter of common knowledge that the physical sensations which we call heat and light are bound up in a common origin and controlled by common laws. Indeed, it is not one of the least achievements of the nineteenth century that it has recognized that the real advances in thought are made not so much by the men of agile logical power as by the men who have stuck patiently to the obstinate facts of the concrete world. Accordingly, in all your explanations, whether your subject be baseball or the nebular hypothesis or a town government or the latest research in history, bear in mind that the ultimate value of your explanation will be its power to help people to order and simplify their real experience. Your explanation of baseball will seem merely perfunctory unless it makes people who read it see the essential character of the game, the special skill of a good player, and what there is in it to make such crowds of people willing to spend time and money to see it and your treatise in history will be vain and unprofitable unless by patient labor in absorbing facts you throw new light on the course of actual, concrete events. As Professor Lamont points out, "abstractions produce little or no effect until translated into concrete terms. If the writer himself does not translate them, the reader must; and this task makes hard reading." In general, the more abstract your explanation the fewer people will take the