Principle of Wisdom Sutra ［理趣経］ ( Ārya-prajnāpāramitā-naya-shatapanchashatikā; Chin Li-ch’ü-ching;  Rishu-kyō): A sutra that depicts Mahāvairochana Buddha preaching to Vajrasattva, who is regarded as one of the eight original patriarchs of Esoteric Buddhism by the True Word ( Shingon) school. The sutra teaches that the true nature of all desires, including sexual desires, is purity, and that this purity of all things and phenomena is realized through the wisdom, or prajnā, that penetrates the truth. It also praises the compassionate actions of bodhisattvas. There exists a Sanskrit text, as well as six Chinese and three Tibetan versions. The translators of the Chinese versions are Hsüan-tsang, Bodhiruchi, Chin-kang-chih ( Vajrabodhi), Pu-k’ung (Amoghavajra), Dānapāla, and Fa-hsien, all of whom, with the exception of Hsüan-tsang, were of Indian origin. Fa-hsien’s Sanskrit name is unknown. Of these six versions, Pu-k’ung’s translation is the most popular and is recited in the True Word school. Hsüan-tsang’s version is included in the six-hundred-volume Great Wisdom Sutra.