An example of the first was the frightful “black death” which swept over Europe in 1348–50, destroying nearly a fourth of the whole population. All accounts agree that the despair and desperation which accompanied such an unexampled affliction showed themselves in an abandonment of all restraint, a reckless indulgence in the wildest debaucheries, an entire disregard of social restrictions. The same is true of the “plague and famine” years, 1491–95, when, in the words of a medical historian, “the corruption of morals reached a height without parallel in ancient times.” The depressing power of sudden defeat and subjugation has been repeatedly exemplified. The “spirit is broken” of the conquered people. Only by such a profound mental depravation can we explain why such a warlike and numerous nation as the Aztecs sank instantly to be the serfs of a handful of white conquerors. A writer on the history of the Christian church has remarked that “every nation has its peculiar heresy.” A student of mental pathology might justly add that every nation has its peculiar form of insanity. An irrational tendency is present and active in every community, ever striving to gain the ascendancy, and when it succeeds, as has often been the case in history, it makes steadily for the destruction and extinction of the national existence. The forms of mental alienation are as various in the collective as in the individual mind, and as they are extensions of the symptoms seen in the latter, they may be classified on similar lines. I shall examine them, therefore, first as they are connected with intellectual and next with emotional disturbances, in accordance with the following scheme: ETHNIC PSYCHOPATHIC CONDITIONS. I.—_In the Intellectual Life._ 1. Conditions of Deficiency │(_a_) Imbecility. │(_b_) Criminality. 2. Conditions of Perversion │(_a_) Delusions. │(_b_) Dominant Ideas. II.—_In the Emotional Life._ 1. Conditions of Hypersthenia (active motor │(_a_) Hysteria. states) │ │(_b_) Exaltation. │(_c_) Destructive │ Impulses. 2. Conditions of Asthenia (passive sensory │(_a_) Melancholia states) │ (Depression). │(_b_) Neurasthenia │ (Exhaustion).