The Yoga-power of the Golden Age men draw disembodied souls from the Bhuba sphere and spiritual souls from higher spheres to enter into a woman's womb and be born on the earth plane. The will-force of these men supplies these incoming souls with the material of a physical body. In the Silver Age the higher illuminated Brāhmans and Saints can bring about conception in the same way, while others bring it about by making the women eat magnetized "charoo," which not only draws these spirits to the womb, but supplies the material for the physical body. In the Copper Age, however, the decrease of spirituality takes away the power, and so the material of the physical body has to be supplied by the physical vigor of the father and the blood of the mother to enable a disembodied spirit to enter the womb and grow into a child. This degenerated process of procreation coming into vogue in the Copper Age renders it necessary to fuse higher magnetism into the lower castes, as well as to preserve the magnetism of each caste from deterioration. The means adapted for securing these ends is to allow the two higher castes men to marry girls of the lower castes, and towards the latter end of the Copper Age even Vaishyas are permitted to marry Sudra girls. The lower caste men, however, are never allowed to marry higher caste women, as it degenerates the breed, the seed being a far more potent factor in producing excellence of growth than the soil. The offsprings of these intermarriages form into castes distinct from those of their fathers and mothers, lower than their father's and higher than their mother's. In order to preserve the magnetism and the hereditary talent and instincts from deteriorating, the castes are divided into sub-castes according to their general proclivities and professions of livelihood. Each sub-caste must marry within its own circle, and must eat food cooked by the hands of its own members. Heredity is now being believed in by the materealistic people of the modern world, and when that belief in heredity will have grown stronger in their minds, they will then take practical measures to preserve the good qualities of heredity from being spoilt by coming in contact with the bad magnetism of its lower traits. This human magnetism is a subject which is worthy of the study of modern scientists. If they can find out what it is, ascertain its properties, power for good and evil, and how good magnetism can be conserved and transmitted and how bad magnetism can be purified, they will do humanity greater good than they have done by the discovery of steam and electricity, which, judged from the standpoint of the highest good, ought to be considered as very doubtful boons. Magnetism is not useful magnetism if it is purely physical. It is not worth preserving, it is injurious, and its contact ought to be avoided.