One of the greatest differences in people is in the organization of their ideas. Of course, people differ in original experience, but they differ more in the way they organize this experience and prepare it for future needs. Just as in habit-formation we should by exercise and practice acquire those kinds of skill that will serve us best in the future, so in getting knowledge we should by repetition strengthen the connections between those ideas that we shall need to have connected in the future. All education looks forward and is preparatory. As a result of training in the organization of ideas, a pupil can learn how to organize his experience, in a measure, independent of the teacher. He learns to know, himself, what ideas are significant, and what connections of ideas will be most helpful. Such an outcome should be one of the ends of school training. =Training in Reasoning.= We have already mentioned ways in which a child can be helped in gaining power and facility in reasoning. In this paragraph we shall discuss the matter more fully. There are three aspects of training in reasoning, one with reference to original experience, one with reference to the organization of this experience as just discussed, and one with reference to certain habits of procedure in the recall and use of experience. (1) _Original experience._ Before reasoning in any field, one must have experience in that field. There is no substitute for experience. After having the experience, it can be organized in various ways, but experience there must be. Experience may be primary, with things themselves, or it may be secondary, received second hand through books or through spoken language. We cannot think without ideas, and ideas come only through perceptions of one kind or another. Originally, all experience arises out of sensations. Language makes it possible for us to profit through the perceptual experience of others. But even when we receive our experience second hand, our own primary experience must enable us to understand the meaning of what we read and hear about, else it is valueless to us. Therefore, if we wish to be able to reason in the field of physics, of botany, of chemistry, of medicine, of law, or of agriculture, we must get experience in those fields. The raw material of thought comes only through experience. In such a subject as physical geography, for example, the words of the book have little meaning unless the child has had original experience in the matter discussed. He must have seen hills and valleys and rivers and lakes and rocks and weathering, and all the various processes discussed in physical geography; otherwise, the reading of the text is almost valueless. The same thing is true of all subjects. To reason in any subject we must have had original experience in it.