IN THE ENTIRE HISTORY OF HUMANKIND, there is no chapter more instructive for the heart and the mind than the annals of human aberrations. For every great crime committed, an equally great force was at work. If the mysterious play of desire is hidden in the faint light of normal emotion, how much more striking, colossal, and transparent it becomes in the state of over-whelming passion. The more sophisticated student of human nature, who knows just how predictable the mechanism of normal free will is, and to what extent it is possible to deduce through analogy, will transfer many an observation from this field into personal knowledge of psychology, and apply this insight in the realm of moral activity.

The human heart is something so simple, and yet so multifaceted. One and the same capacity or desire can play out in thousands of shapes and directions, can cause thousands of contradictory phenomena, can appear in different combinations in thousands of characters, and thousands of dissimilar characters and events can be spun from the one and the same impulse, even if the individual in question never recognizes the relationship of his actions to those of the rest. If a new Linnaeus were to appear and classify humankind into genus and species according to drives and inclinations, how astonished we would be to find those whose vice must now suffocate in a constricted bourgeois sphere and the narrow confines of the law, together in one and the same species with a monster like Cesare Borgia.