Along with the question of heredity stands that of the development of races. In the beginning of the _Origin of Species_ Darwin showed how essential pure descent is for the production of a noble race. This theory is appealed to by a modern anti-Semitic writer, who represents the Jew as a typical example of pure race, an idea which one of the most conspicuous representatives of Judaism, Disraeli, has also expressed in the following words: "Race is everything; there is no other truth, and every race which carelessly allows mixed blood, perishes." Yet other specialists consider some racial mixture as highly advantageous to the offspring. Professor Westermark has offered a good reason for the significance attached to beauty in the case of love, and therefore its importance for the race. He has shown how man has conceived physical beauty to be the full development of all of those characteristics which distinguish the human organism from the animal, and which mark sex distinctions, and, most of all, race distinctions. He thinks individuals with these characteristics are best suited for their life work. Accordingly it is the result of natural selection that exactly those individuals are found most beautiful and are most desired, who first as human beings best fulfil the general demands of the human organism, as sexual beings fulfil those of their sex, and as members of the race are best suited to the conditions which surround them. In the struggle for existence, those are overcome, who are descended from human beings, whose instincts of love are directed to individuals badly adapted to that struggle; while those who are victorious are children happily so adapted. In this way, taste has developed by which, what is best adapted to environment appears as the highest beauty. This is equivalent to health, the power to resist the attacks of the external world. While every considerable deviation from the pure type in sex and race, has a lesser degree of adaptability; that is of health, and also of beauty. Another writer has used the foot as an example of this principle. The small, high-arched foot with the fine ankle is always, he says, regarded as the most beautiful. But such a foot is only combined with a fine, strong, and elastic bony structure. Such a foot besides has, by its great elasticity, a considerably higher power of bearing weight than the flat foot. The high-vaulted foot, in walking and jumping, increases the activity of the lungs and the heart. This again makes the walk elastic, strong, and easy, agile and stately. These traits, for the same reason as the beauty of the foot itself, are looked upon as a racial sign. This physical power and ease influence the mind, and produce self-confidence, and so increase the feeling of superiority and the joy of living, marks of distinction in human beings.