Another point in the cultivation, training, and restraint of the emotions is that which has to do with the control of the ideas which we allow to come into the mind. Ideative habits may be formed--_are_ formed, in fact, by the majority of persons. We may cultivate the habit of looking on the bright side of things; of looking for the best in those we meet; of expecting the best things instead of the worst. By resolutely refusing to give welcome to ideas calculated to arouse certain emotions, feelings, passions, desires, sentiments, or similar mental states, we may do much to prevent the arousing of the emotion itself. Emotions usually are called forth by some idea, and if we shut out the idea we may prevent the emotional feeling from appearing. In this connection the universal rule of psychology may be applied: _A mental state may be inhibited or restrained by turning the attention to the opposite mental state_. The control of the attention is really the control of every mental state. We may use the will in the direction of the control of the attention--the development and direction of voluntary attention--and thus actually control every phase of mental activity. The will is nearest to the ego, or central being of man, and the attention is the chief tool and instrument of the will. This fact cannot be repeated too often. If it is impressed upon the mind it will prove to be useful and valuable in many emergencies of mental life. He who controls his attention controls his mind, and in controlling his mind controls himself. CHAPTER XII. The Instinctive Emotions. Many attempts to classify the emotions have been made by the psychologists, but the best authorities hold that beyond the purpose of ordinary convenience in considering the subject _any_ classification is scientifically useless by reason of its incompleteness. As James cleverly puts it: "Any classification of the emotions is seen to be as true and as natural as any other, if it only serves some purpose." The difficulty attending the attempted classification arises from the fact that every emotion is more or less complex, and is made up of various feelings and shades of emotional excitement. Each emotion blends into others. Just as a few elements of matter may be grouped into hundreds of thousands of combinations, so the elements of feeling may be grouped into thousands of shades of emotion. It is said that the two elements of carbon and hydrogen form combinations resulting in five thousand varieties of material substance, "from anthracite to marsh gas, from black coke to colorless naphtha." The same thing may be said of the emotional combinations formed from two principal elements of feeling. Moreover, the close distinction between sensation and feeling on the one hand, and between feeling and emotion on the other, serves to further complicate the task.