can only be sought and essayed in the science of moral psychology (this, in fact, is my most general formula for what is generally called a “ religion ”). Such a feeling of depression can have the most diverse origins; it may be the result of the crossing of too heterogeneous races (or of classes⁠—genealogical and racial differences are also brought out in the classes: the European “Weltschmerz,” the “Pessimism” of the nineteenth century, is really the result of an absurd and sudden class-mixture); it may be brought about by a mistaken emigration⁠—a race falling into a climate for which its power of adaptation is insufficient (the case of the Indians in India); it may be the effect of old age and fatigue (the Parisian pessimism from 1850 onwards); it may be a wrong diet (the alcoholism of the Middle Ages, the nonsense of vegetarianism⁠—which, however, have in their favour the authority of Sir Christopher in Shakespeare); it may be blood-deterioration, malaria, syphilis, and the like (German depression after the Thirty Years’ War, which infected half Germany with evil diseases, and thereby paved the way for German servility, for German pusillanimity). In such a case there is invariably recourse to a