In the Brihadaranyaka Upanishad, "ekayāna" took on special significance as a metaphor for a spiritual journey. The phrase vedānāṃ vāk ekayānam translates approximately to "the one destination of the Vedas is the spirit of the word".[1][2]
While the "One Vehicle" Buddhism declined in India along with the rest of Buddhism, it became a key aspect of the Chinese acculturation and acceptance of Buddhism. The Chinese assimilation of Buddhism met in the vast diversity of Buddhist texts the problem of sorting through them for the core of Buddhist teaching.[citation needed]
This problem was solved by Chinese Buddhist teachers by taking up one or more of the Ekayana Sutras as central to the understanding of the diversity of Buddhism. The doctrines and practices of Tiantai (Japanese Tendai) and Huayen (Japanese Kegon) Buddhist sects were able to present a synthesis of the diversity of Buddhism that was understandable and palatable by the Chinese worldview.[citation needed]
Chan Buddhism affected this synthesis in a unique way by focusing on the practice of meditation as taught in the Laṅkāvatāra Sūtra as the core method of personally realizing the Ekayana teachings while at the same time acknowledging the transcendental and devotional aspects represented by the Avatamsaka Sutra and the Lotus Sutra, respectively.[citation needed] The Indian Buddhist monk Bodhidharma (c. 5th to 6th century), who is considered the founder of Chan Buddhism, was said to have brought the "Ekayāna school of Southern India" to China and passed it down along with the Laṅkāvatāra Sūtra to his primary disciple, Dazu Huike (487-593), known as the Second Founding Ancestor of the Chan lineage.[7], [8][page needed]
Guifeng Zongmi (780 - 841) was an accredited master of both the Chan and Huayan lineages. In his treatise, The Original Person Debate (Chinese: 原人論), he explicitly identifies the Ekayāna teachings as the most profound type of spiritual realization and equates it with the direct realization of one's own nature:
Buddha's teaching itself goes from shallow to profound. In outline there are five classes: 1. The teachings of human and heavenly beings. 2. The Small Vehicle's (Hinayana) teaching. 3. The Great Vehicle's (Mahayana) teaching of Dharma characteristics (dharmalaksana). 4. The Great Vehicle's teaching of destroying characteristics. 5. The One Vehicle's (Ekayana) teaching of manifesting Nature."[9]
Thus, according to Zongmi who was a lineage master of both Huayan and Chan, he clearly distinguished the Ekayana from the Mahayana, and the Mahayana teachings of Yogacara (his Mahayana class 3) and Madhyamaka (his Mahayana class 4) were eclipsed by the more profound Ekayana teaching of "manifesting nature."
^Vaidya, P. L. (1960). SaddharmapuṇḍarīkasūtramArchived 2014-10-13 at the Wayback Machine, Darbhanga: The Mithila Institute of Post-Graduate Studies and Research in Sanskrit Learning. (Romanized Sanskrit)
^D.T. Suzuki in his Studies in the Lankavatara Sutra relates a portion of the biography of Fa-ch'ung on his special relationship with the Lankavatara Sutra: "Fa-ch'ung, deploring very much that the deep signification of the Lankavatara had been neglected for so long, went around everywhere regardless of the difficulties of travelling in the far-away mountains and over the lonely wastes. He finally came upon the descendants of Hui-k'e among whom this sutra was being studied a great deal. He put himself under the tutorship of a master and had frequent occasions of spiritual realisation. The master then let him leave the company of his fellow-students and follow his own way in lecturing on the Lankavatara. He lectured over thirty times in succession. Later he met a monk who had been instructed personally by Hui-k'e in the teaching of the Lankavatara according to the interpretations of the Ekayana (one-vehicle) school of Southern India." (pp. 51-52.)
^Yampolsky, Philip B. (1967). The Platform Sutra of the Sixth Patriarch(PDF). Columbia University Press. Archived from the original(PDF) on 21 May 2015. Retrieved 19 May 2015. In the biography of Fa-ch'ung in the Hsu kao-seng chuan, T50, p. 666b, there is mention of the 'One-vehicle sect of India (Nan-t'ien-chu i-ch'eng tsung)' in reference to Bodhidharma's teaching.
Nattier, Jan (2007). One Vehicle in the Chinese Agamas, Annual Report of The International Research Institute for Advanced Buddhology at Soka University 10, 181-200
Pye, Michael (2003). Skilful Means - A concept in Mahayana Buddhism. Routledge. ISBN0203503791.