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 belief in the continuance of human existence in animals and trees. If, therefore, the Aryan Indians borrowed the idea from the aborigines, they certainly deserve the credit of having elaborated out of it the theory of an unbroken chain of existences, intimately connected with the moral principle of requïtal. The immovable hold it acquired on Indian thought is doubtless due to the satisfactory explanation it offered of the misfortune or prosperity which is often clearly caused by no action done in this life. Indeed, the Indian doctrine of transmigration, fantastic though it may appear to us, has the twofold merit of satisfying the requirement of justice in the moral government of the world, and at the same time inculcating a valuable ethical principle which makes every man the architect of his own fate. For, as every bad deed done in this existence must be expiated, so every good deed will be rewarded in the next existence. From the enjoyment of the fruits of actions already done there is no escape; for, in the words of the Mahabharata, "as among a thousand cows a calf finds its mother, so the deed previously done follows after the doer."