'I'm sure they know, but I think you don't ask the question quite rightly. Let me try.' So, taking the book, she asked: 'In what condition is the interior of the globe?' and received the immediate answer from half the class at once; 'The interior of the globe is in a condition of igneous fusion!'"

Perhaps it may be thought that an incident like the foregoing would only occur in an elementary school. As a matter of fact, college students and graduates, and indeed most of us, do this very thing more often than we realize, even in subjects like mathematics or mechanics; and terms like "energy," "momentum," "rate of change," "period of vibration," "value," "social justice," etc., are often used without a clear understanding, and sometimes without any understanding at all, of what they mean.

(a) THE STUDENT SHOULD ACQUIRE AND INSIST UPON EXERCISING THE HABIT OF FORMING DEFINITE IDEAS.—This is one of the most important injunctions to be observed as an essential principle of intelligent study.[1] It is self-evident that facts or things cannot be reasoned about intelligently unless a definite idea is formed of the facts or things themselves. Vagueness of idea not alone precludes a proper conception of the thing itself, but may vitiate all reasoning regarding it. The student must resolutely make up his mind that he must not rest satisfied with hazy, uncertain, half-formed ideas. A half knowledge of a thing may not be useless, but it is generally found that it is the other half that is needed. If the student could learn this one precept and continually apply it, he would have little difficulty in studying properly.

It is not easy to state just how the habit of forming definite ideas may be acquired. To a certain extent it is intuitive. Some students have it, while others do not; some can cultivate it, while others apparently cannot. It is probably safe to say, however, that a student who cannot cultivate it should not study books, or enter into a profession, but should go to work with his hands instead of taking a college course. Such a man will be always likely to be misled, his conclusions can never be depended upon, and what we term education may do him harm rather than good.

A definite idea is one that leaves no room for ambiguity—which means just one thing. The habit of forming such ideas habitually may be cultivated in several ways, as for instance:

1. STUDY THE DICTIONARY.—By study of the dictionary, the student may train himself to distinguish slight differences in meaning between words, and habitually to use precisely the word with the proper meaning to express his idea. A knowledge of the derivation of words will often assist, and such books as Archbishop Trench's on "The Study of Words," or a course in English composition under a good teacher, accompanied by exercises in expression, will all contribute to the formation of the habit.[2] Sometimes, however, the dictionary may give little assistance, for it may be found that one term is defined by means of another and on looking up that other, it will be found to be defined by means of the first. Sometimes also a definition of a word will be given in terms even more difficult to understand than the one which is defined. There are differences in dictionaries. The study of language, and particularly of the classics, if properly pursued, may be of great benefit, because it involves translating from one language into another, and should include much practice in discovering the precise word or phrase to express an idea. The reason why a study of the classics may be better than that of modern foreign languages, is that in studying the latter the object is more often considered—by the student at least—to become able to read professional books in a modern language, or to get a smattering which will be of use in travel or in business; while in the study of the classics these objects are entirely absent, and the attention is more apt to be concentrated on studying delicate shades of meaning. However, everything depends upon the teacher and the way the subject is taught.[3]

2. The habit of forming definite ideas may also be cultivated by each day attempting to define a certain number of common words, and after making as good a definition as possible comparing the result with that in the dictionary. If the student will practise this, he will at first receive many surprises, for any word may be defined in various ways, all correct as far as they go, but only one of which is a true definition. For instance, a cow may be defined as a four-legged animal, but this, while correct, obviously does not define a cow, for the same definition would apply to many other animals that are not cows. What constitutes a definition?

This subject is clearly allied with the discussion of the question as to what constitutes perfect knowledge; what elements, for instance, go to make up what may be called a perfect conception of a thing. According to Liebnitz, perfect knowledge is clear, distinct, adequate, and intuitive. The student will do well to look up the discussion of this subject in Jevon's "Elementary Lessons in Logic" (Lesson VII).

The importance of forming definite ideas, as an essential of proper study, and of understanding what is read, cannot be exaggerated. Without it one cannot acquire more than a partial knowledge, and one is always liable to those errors of reasoning which arise from the use of equivocal language, which may lead us unconsciously from one meaning of a word to another—a logical error which is perhaps the most fruitful cause of fallacious reasoning.

3. STUDY LOGIC.—Logic is the science of correct reasoning. It teaches us how to discover truth, how to recognize it when discovered, how to arrive at general laws from facts collected by observation or experiment, and how to deduce new facts from those already found to be true. It is thus the science of sciences, and finds its application in every branch of knowledge. The training of his power of logical thought is, therefore, one of the things that should be constantly aimed at by the student.

Now all thinking is concerned, first of all, with terms or names for things or qualities or conceptions of some sort. Then, it is concerned with comparisons of things, and the discovery of their identity or dissimilarity, as when I say "Iron is a metal" or "all metals are elements," each of which statements is a proposition, the truth or falsity of which I must be able to discover. Finally, it is concerned in deducing new propositions from old ones, and so arriving at new truths, as when I discover from the two propositions stated above, the new truth that "Iron is an element."

But there are many chances for error in this process; for instance, I might say:

"To call you an animal would be to state the truth"—to which you would agree; and, "To call you an ass would be to call you an animal"—to which you would also agree; from which I might conclude that, "To call you an ass would be to state the truth"—which you might have a vague idea was not true. If you wish to be sure that this conclusion is incorrect, you must