Ideas may be clarified in two ways: by definition and by classification. Definition is a familiar device, for you have had much to do with it in learning. The memorization of definitions is an excellent practice, not as an end in itself, but as a means to the end of effective reasoning. Throughout your study, then, pay much attention to definitions. Some you will find in your texts, but others you will have to make for yourself. In order to get practice in this, undertake the manufacture of a few definitions, using terms such as charity, benevolence, natural selection. This exercise will reveal what an exacting mental operation definition is and will prove how vague most of your thinking really is. A large stock of definitions will help you to think rapidly. Standing as they do for a large group of experiences, definitions are a means of mental economy. For illustration of their service in reasoning, suppose you were asked to compare the serf, the peon and the American slave. If you have a clean-cut definition of each of these terms, you can readily differentiate between them, but if you cannot define them, you will hardly be able to reason concerning them. The second means of clarifying ideas is classification. By this is meant the process of grouping similar ideas or similar points of ideas. For example, your ideas of serf, peon and slave have some points in common. Group the ideas, then, with reference to these points. Then in reasoning you can quickly place an idea in its proper group. The third stage of the reasoning process is decision, based on belief, and it comes inevitably, provided the other two processes have been performed rightly. Accordingly, we need say little about its place in study. One caution should be pointed out in making decisions. Do not make them hastily on the basis of only one or two facts. Wait until you have canvassed all the ideas that bear importantly upon the case. The masses that listen top eagerly to the demagogue do not err merely from lack of ideas, but partly because they do not utilize all the facts at their disposal. This fault is frequently discernible in impulsive people, who notoriously make snap-judgments, which means that they decide before canvassing all the evidence. This trait marks the fundamental difference between superficial and profound thinkers. The former accept surface facts and decide immediately, while the latter refuse to decide until after canvassing many facts.