Ch'eng wei shih lun is a commentary to Vasubandhu's work Triṁśikā. It was compiled by the Chinese scholar Xuanzang (Hsüan-tsang, 602–664) on the basis of materials he collected when on pilgrimage in India. Its affiliation is to the Yogācāra school of Buddhist Philosophy (also known as Vijñānavāda) often referred to as the ‘Mind-only’ (citta-mātra or vijñaptimātra) teaching. Its basic tenet is the denial of the independent existence of material things and the whole external world outside consciousness. However, it recognises several layers of consciousness and the eighth one, called ‘storehouse’ consciousness (ālaya vijñāna), preserves impressions (vāsanās) of past experiences and seeds (bījās) of karmic actions. When these mature (become vipākavijñāna), the minds of individual beings project them outwards and perceive them as objects and events in an external world around them which shape their lives. The world, thus projected, appears to be shared by beings, or perhaps better expressed, the worlds projected by individuals appear to overlap, hence the assumption that individual ālaya vijñānas also overlap or have a common ground. This seems to be corroborated by the view, expressed in Laṅkāvatāra-sūtra, that ālaya vijñāna harbours Buddha nature, also termed tathāgatagarbha or ‘womb of buddhahood’, in other words, that every being has deep inside himself the potential to become a Buddha.

In the context of western philosophical thought the idea that there is no external world is regarded as an ontological stance and therefore Yogācāra philosophy has been classified as phenomenological idealism. However, recently this classification has been challenged. The author singles out a work by Dan Lusthaus, Buddhist Phenomenology. A Philosophical Investigation of Yogācāra Buddhism and the Ch'eng wei shih lun (Routledge Curzon, London, 2002) from which it transpires that Lusthaus suggests that Yogācāra's phenomenological idealism need not imply ontological commitment; its ‘mind-only’ stance may be just a ‘therapeutical device’ or soteriological strategy aimed at detachment from the world, but need not rule out existence of matter (rūpa) independent of mind in the same way as other beings' minds exist independently of one's own mind. This would mean that although we know about external objects and other minds only through our mind, they still may exist independently from it.

Leaving Lusthaus's philosophical interpretations aside, the author, “not being a philosopher”, decided to examine the relevant passage of Xuanzang's text on the basis of internal interpretation. He dedicated to it the bulk of the work under the heading ‘Discussion of the Basic Evidence’ which abounds in quotations, some of them in Chinese, lengthy footnotes, translations and re-translations of portions of Xuanzang's text, some commentaries to it and other works dealing with the problem. I am not quite sure that the interpretation the author has finally arrived at can be seen as limited to purely internal (textual) evidence without an element of philosophical argumentation. On some level we all are philosophers so that his disclaimer need not be taken seriously. But his arguments appear sound. In any event, his conclusion is that Xuanzang's Ch'eng wei shih lun does not allow for the independent existence of the external world.

The work finishes with a piece on ‘The Spiritual Context of vijñaptimātratā’ in which the author points out that Buddhism is concerned with sentient beings and their intentions which result in either karmic effects or liberation. It is therefore mental factors which produce their world or their experience of the highest truth or true reality (tathatā). This strengthens the argument for the mind-only (vijñaptimātra) understanding of the nature of the world. To regard it as independent of mind is, from this point of view, a misconception from which Buddhas and Bodhisattvas are free even when they enter the karmically produced worlds/minds (vipākavijñānas) of other beings to help them transform their impure worlds into pure ones and share with them their Buddha fields or the final freedom.

The mind-only doctrine is certainly a feasible philosophical conception of reality. As developed in Buddhist texts it has the advantage over once favoured idealistic trends in western philosophy in that it cannot fall into the trap of solipsism. It even shows affinity with the modern scientific view, which has dissolved matter into subatomic processes and recognises the role of the observer in determining their outcome. There is nothing in it which could be seen as distortion of the Buddhist message and hinder its practical purpose. There are even passages in the early Pāli sources from which, as a starting point, the mind-only doctrine could have been developed. And the suggestion voiced by Lusthaus that it may have been understood in some quarters as a soteriological strategy without an ontological commitment cannot be ruled out. That would bring it even more in line with the early Pāli texts in which the Buddha discourages speculation and recommends just practising the spiritual path to develop direct rather than conceptual knowledge of reality.

This small work is meant for specialists and its style is not easy. Nevertheless, even without being able to check its arguments against the Chinese texts which it refers to, working through the author's arguments is worthwhile and useful for grasping the subtleties of the doctrine.