We have, in the doctrine of transmigration of souls, however, a sufficient explanation of the special association between a particular totem and the members of the gens or family group to which it gives name. According to that doctrine,[356] as stated in the Hindoo code, known as the Laws of Menu (chap. xii.), “with whatever disposition of mind a man shall perform in this life any act, religious or moral, in a future body endued with the same quality, shall he receive his retribution.” Numerous animals are named as proper for such re-incarnation, and even vegetables and mineral substances appear among them. Transmigration seems to have been considered by Oriental teaching essential to the attainment of perfection by the human soul, and the forms through which it is supposed to pass, include not only beasts, birds, and fishes, but also trees, stones, and other inanimate objects. The great Gautama himself is said to have passed through all the existences of earth, air, and sea, as well as through all the conditions of human life, before he became the Buddha. Dr. M’Lennan says[357] it is of the essence of the doctrine of transmigration that “everything has a soul or spirit, and that the spirits are mostly human in the sense of having once been in human bodies.” We have here the key to the problem of totemism, which receives its solution in the idea that the totem is _the re-incarnated form of the legendary ancestor of the gens or family group allied to the totem_. The belief that the spirits of the dead do take on themselves animal forms is widely spread.[358] The most remarkable example of this belief is that which views certain snakes, not merely as re-incarnations of human souls, but as re-embodiments of ancestors of the people by whom such snakes are venerated. Serpent-worship is, indeed, closely connected with the worship of ancestors. The followers of the serpent believed themselves “to be of the serpent-breed, derived from a serpent ancestor,” and we know that peoples have claimed to belong to the serpent race. Such a claim, or that to a monkey relationship made by some of the dark tribes of India, would be readily admitted by the savage mind, and it may be explained on the principle that the legendary ancestor of the race is supposed to have become re-incarnated in monkey or snake form, and that monkeys or snakes as well as men are his descendants.