Two Main Streams of Thought in Yogācāra Philosophy
In the tradition of Buddhism which has been transmitted to China and Japan, we can see two basically different streams of thought in the Yogācāra philosophy. Although this fact is well-known among Japanese scholars, it does not seem to be widely known among American, European, and Indian scholars. In order to understand correctly the Yogācāra philosophy, however, the clear understanding of these two streams of thought, their mutual differences, and their relation to the theories of Maitreya, Asaṅga, and Vasubandhu is indispensable
One of these two streams was introduced into China by Hsuang-tsang. Although the thought of this stream can be known through the works of Maitreya, Asaṅga, and Vasubandhu as translated by Hsuang-tsang, it can be known in its most all-inclusive and systematic form in the Ch'eng wei shih lun of Dharmapāla. This stream of thought continued from the time of Hsuang-tsang to the present day. Happily, it did not die out in China and Japan where its study was continued and where present-day scholars are well acquainted with it. There is no unclear point as regards the more important aspects of this stream of thought.
The other stream of thought, represented by the works of Maitreya, Asaṅga, and Vasubandhu as translated by Buddhasānta, Bodhiruci, Paramārtha, Dharmagupta, Prabhākaramitra, and others, was introduced into China before the time of Hsuang-tsang. The translations of these masters, unlike those of the other stream, were not widely studied and the actual nature of its thought is difficult to determine. With the exception of Paramārtha, there are only one or two translated works of each of these masters. And, even in the study of their works, it is not possible to determine the differences from the other stream of Yogācāra thought.
Paramārtha, however, translated a great many of the important works of Maitreya, Asaṅga, and Vasubandhu. And, with the discovery and publication of the Sanskrit texts, eminent scholars of Japan have done comparative studies based on the Sanskrit original and the Chinese and Tibetan translations in order to determine the extent to which the stream of thought introduced into China before the time of Hsuang-tsang differs from that stream which was introduced by Hsuang-tsang. The results of this research clearly show that there is a fundamental difference between the theory introduced by Paramārtha and that of Hsuang-tsang. The importance of this difference lies in the fact that the theories introduced by Paramārtha and Hsuang-tsang are both said to be the theories of Maitreya, Asaṅga, and Vasubandhu. If the theories of Paramārtha and Hsuang-tsang are fundamentally different, the problem arises as to which transmission is faithful to the theories of Maitreya, Asaṅga, and Vasubandhu; or, if they are both separate traditions, what was the theory of Maitreya, Asaṅga, and Vasubandhu? This has been the focus of attention of present-day Japanese scholars doing research in the Yogācāra philosophy. As the studies of the Yogācāra philosophy by Western and Indian scholars have been lacking in knowledge of these two streams of thought, their interpretations of the central problems of the Yogācāra philosophy have been ambiguous and often erroneous and do not show a clear understanding of it. Their understanding of the Yogācāra philosophy is not in accord with the theory of either one of these two streams of thought. And, because the differences between their interpretations and the two streams of thought are not clear, one cannot find a clear-cut understanding of the theories of Maitreya, Asaṅga, and Vasubandhu.
It is my aim in this paper to present the differences of interpretation of these two streams of thought relating to the theories of Maitreya, Asaṅga, and Vasubandhu which were transmitted to China and to examine the question of which of the two streams is faithful to the thought of Maitreya, Asaṅga, and Vasubandhu. As this paper cannot possibly deal with the whole of the Yogācāra philosophy, it will deal with only a few of the essential points. (Ueda, preparatory remarks, 155–56)