Thus the theory of the three bodies, especially of the Dharma-kâya, is bound up with a theory of ontology. Metaphysics became a passion among the travellers of the Great Vehicle as psychology had been in earlier times. They may indeed be reproached with being bad Buddhists since they insisted on speculating on those questions which Gotama had declared to be unprofitable and incapable of an answer in human language. He refused to pronounce on the whence, the whither and the nature of things, but bade his disciples walk in the eightfold path and analyse the human mind, because such analysis conduces to spiritual progress. India was the last country in the world where such restrictions were likely to be observed. Much Mahayanist literature is not religious at all but simply metaphysics treated in an authoritative and ecclesiastical manner. The nature and origin of the world are discussed as freely as in the Vedânta and with similar results: the old ethics and psychology receive scant attention. Yet the difference is less than might be supposed. Anyone who reads these treatises and notices the number of apparently eternal beings and the talk about the universal mind is likely to think the old doctrine that nothing has an âtman or soul, has been forgotten. But this impression is not correct; the doctrine of _Nairâtmyam_ is asserted so uncompromisingly that from one point of view it may be said that even Buddhas do not exist. The meaning of this doctrine is that no being or object contains an unchangeable permanent self, which lives unaltered in the same or in different bodies. On the contrary individual existences consist of nothing but a collection of skandhas or a _santâna_, a succession or series of mental phenomena. In the Pali books this doctrine is applied chiefly to the soul and psychological enquiries. The Mahayana applied it to the external world and proved by ingenious arguments that nothing at all exists. Similarly the doctrine of Karma is maintained, though it is seriously modified by the admission that merit can be transferred from one personality to another. The Mahayana continued to teach that an act once performed affects a particular series of mental states until its effect is exhausted, or in popular language that an individual enjoys or suffers through a series of births the consequences of previous acts. Even the instance of Amitâbha's paradise, though it strains the doctrine of Karma to the utmost, does not repudiate it. For the believer performs an act--to wit, the invocation of Amitâbha--to which has been attached the wonderful result that the performer is reborn in a blessed state. This is not essentially different from the idea found in the Pali Canon that attentions paid to a Buddha may be rewarded by a happy rebirth in heaven.[100]