The work, written by Tripitaka Master Sywan Dzang (AD 596-664) at the request of his foremost disciple and successor Dharma Master Kwei Ji (AD 632-682), is a summary of the doctrine contained in Hsuan-Tsang's most celebrated work, Treatise on Consciousness-Only. The Treatise on Consciousness-Only is a commentary on the Thirty Verses on Consciousness Only by the Bodhisattva Vasubandhu (fl. 4th cent AD). The Treatise is based on the Sanskrit commentary of the Venerable Dharmapala (fl. 6th cent. AD) and nine other Indian masters. Dharmapala was the teacher of Master Sywan Dzang's own teacher, Silabhadra, the Abbot of Nalanda Monastery in India.
Vasubandhu's Thirty Verses on Consciousness Only is in turn a verse summary of the major systematic work of the Consciousness-Only, the Treatise on the Stages of Yoga Practice, which is alternately attributed to Vasubandhu's older brother the Bodhisattva Asanga (fl. 4th cent. AD) according to the Tibetan tradition or to Asanga's supramundane master the Bodhisattva Maitreya according to the Chinese tradition. At any rate according to Sywan Dzang's biography (Hui-li, Life of Hsuan Tsang) Asanga entered samadhi and ascended to the inner courtyard of the Tusita Heaven to learn the doctrine of Consciousness-Only from the Bodhisattva Maitreya.
In brief, the Verses Delineating the Eight Consciousnesses is a verse summary of a commentary on a verse summary of the Treatise on the Stages of Yoga Practice. Only a simple explanation of the meaning of the lines of the Verses is presented here.
The starting point of the Consciousness-Only School is that everything is created from the mind as is "consciousness-only". Everything, from birth and death to the cause of attaining nirvana, is based upon the coming into being and the ceasing to be of consciousnesss, that is, of distinctions in the mind. Consciousness-Only doctrine is characterized by its extensive and sophisticated inquiry into the characteristics of dharmas. For if we can distinguish what is real from what is unreal, if we can distinguish what is distinction-making consciousness and not mistake it for the originally clear, pure, bright enlightened mind, then we can quickly leave the former and dwell in the latter. Ch'an Master Han-shan (AD 1546-1623) has said, "When Consciousness-Only was made known to them (i.e., those of the Hinayana vehicles), they knew that [all dharmas] had no existence independent from their own minds. If one does not see the mind with the mind, then no characteristic can be got at. Therefore, in developing the spiritual skill necessary for meditative inquiry, people are taught to look into what is apart from heart, mind, and consciousness and to seek for what is apart from the states of unreal (polluted) thinking."