The transformation of simple into derivative emotions, _by arrest of development_, is of less frequent occurrence. While, in the preceding case, there was a forward movement in a straight line, intellectual evolution involving emotional evolution according to the law of transference, here the mental process is more complicated; it supposes an antagonism between two states of consciousness, resolving itself into a compromise. There are, on the one hand, emotional tendencies going in the direction of impulse; on the other, images, ideas, intellectual states of all sorts acting by way of arrest, so that the resultant emotion is composed at the same time of movements and inhibitions of movement. Except fear, all primary emotions imply tendencies to movement, sometimes blind and violent, like natural forces. This is seen in infants, animals, savages, the Barbarians of the first centuries of our era as depicted by contemporary chroniclers; the passage of emotion into action, good or bad, is instantaneous, rapid, and fatal as a reflex movement. Reflection is, by its nature, slow and inhibitory. How can an image or a conception produce an arrest of movement? This is a very obscure question, the psychological and physiological mechanism of which has had but little light thrown on it; it is useless to treat it here in a cursory manner; we need only remark that the arrest exists as a matter of fact. The intervention of this new factor, reflection, may result in two ways. On the one hand, it may obstruct and finally suppress; thus a passion kept in check ends, after various oscillations backward and forward, in being altogether extinguished. The second is a transformation or metamorphosis by arrest of development; the passion is not extinguished, but it has changed its nature. The biological sciences have familiarised us with the notion of arrested development and the morphological modifications resulting therefrom. We know that the parts of a living being are so closely connected that none can change without involving a change on the part of the others; such is the formula of the “Law of Organic Correlations,” and it has its equivalent in the functional order. The “compensation of development” exists beyond all doubt in psychology, though it has not been as much studied as it deserves; thus experience shows us that hypertrophy of certain faculties entails as a consequence the hypertrophy or atrophy of certain others.