The student who is familiar with the processes by which the various schools of Mental Science, etc., produce changes in the mental states of those following their teachings, may not readily understand the principle underlying many of these changes. When, however, the Principle of Polarity is once grasped, and it is seen that the mental changes are occasioned by a change of polarity-a sliding along the same scale-the hatter is readily understood. The change is not in the nature of a transmutation of one thing into another thing entirely different-but is merely a change of degree in the same things, a vastly important difference. For instance, borrowing an analogy from the Physical Plane, it is impossible to change Heat into Sharpness, Loudness, Highness, etc., but Heat may readily be transmuted into Cold, simply by lowering the vibrations. In the same way Hate and Love are mutually transmutable; so are Fear and Courage. But Fear cannot be transformed into Love, nor can Courage be transmuted into Hate. The mental states belong to innumerable classes, each class of which has its opposite poles, along which transmutation is possible. The student will readily recognize that in the mental states, as well as in the phenomena of the Physical Plane, the two poles may be classified as Positive and Negative, respectively. Thus Love is Positive to Hate; Courage to Fear; Activity to Non-Activity, etc., etc. And it will also be noticed that even to those unfamiliar with the Principle of Vibration, the Positive pole seems to be of a higher degree than the Negative, and readily dominates it. The tendency of Nature is in the direction of the dominant activity of the Positive pole.