Dharmmakîrtti (writer of Nyâyabindu 635 A.D.), Vinîtadeva and S'ântabhadra (commentators of Nyâyabindu), Dharmmottara (commentator of Nyâyabindu 847 A.D.), Ratnakîrtti (950 A.D.), Pa@n@dita As'oka, and Ratnâkara S'ânti, some of whose contributions have been published in the _Six Buddhist Nyâya Tracts_, published in Calcutta in the _Bibliotheca Indica_ series. These Buddhist writers were mainly interested in discussions regarding the nature of perception, inference, the doctrine of momentariness, and the doctrine of causal efficiency (_arthakriyâkâritva_) as demonstrating the nature of existence. On the negative side they were interested in denying the ontological theories of Nyâya and Sâ@mkhya with regard to the nature of class-concepts, negation, relation of whole and part, connotation of terms, etc. These problems hardly attracted any notice in the non-Sautrântika and non-Vaibhâ@sika schools of Buddhism of earlier times. They of course agreed with the earlier Buddhists in denying the existence of a permanent soul, but this they did with the help of their doctrine of causal efficiency. The points of disagreement between Hindu thought up to S'a@nkara (800 A.D.) and Buddhist thought till the time of S'a@nkara consisted mainly in the denial by the Buddhists of a permanent soul and the permanent external world. For Hindu thought was more or less realistic, and even the Vedânta of S'a@nkara admitted the existence of the permanent external world in some sense. With S'a@nkara the forms of the external world were no doubt illusory, but they all had a permanent background in the Brahman, which was the only reality behind all mental and the physical phenomena. The Sautrântikas admitted the existence of the external world and so their quarrel with Nyâya and Sâ@mkhya was with regard to their doctrine of momentariness; their denial of soul and their views on the different ontological problems were in accordance with their doctrine of momentariness. After the twelfth century we do not hear much of any new disputes with the Buddhists. From this time the disputes were mainly between the different systems of Hindu philosophers, viz. Nyâya, the Vedânta of the school of S'a@nkara and the Theistic Vedânta of Râmânuja, Madhva, etc. 169 CHAPTER VI THE JAINA PHILOSOPHY The Origin of Jainism.