former life, was already so firmly established in the sixth century B.C., that Buddha received it without question into his religious system; and it has dominated the belief of the Indian people from those early times down to the present day. There is, perhaps, no more remarkable fact in the history of the human mind than that this strange doctrine, never philosophically demonstrated, should have been regarded as self-evident for 2500 years by every philosophical school or religious sect in India, excepting only the Materialists. By the acceptance of this doctrine the Vedic optimism, which looked forward to a life of eternal happiness in heaven, was transformed into the gloomy prospect of an interminable series of miserable existences leading from one death to another. The transition to the developed view of the Upanishads is to be found in the Çatapatha Brāhmaṇa (above, p. 223).
How is the origin of the momentous doctrine which produced this change to be accounted for? The Rigveda contains no traces of it beyond a couple of passages in the last book which speak of the soul of a dead man as going to the waters or plants. It seems hardly likely that so far-reaching a theory should have been developed from the stray fancies of one or two later Vedic poets. It seems more probable that the Aryan settlers received the first impulse in this direction from the aboriginal inhabitants of India. As is well known, there is among half-savage tribes a wide-spread belief that the soul after death passes into the trunks of trees and the bodies of animals. Thus the Sonthals of India are said even at the present day to hold that the souls of the good enter into fruit-bearing trees. But among such races the notion of transmigration does not go beyond a