[2] The trikaya doctrine (Sanskrit, literally "three bodies" or "three personalities") is a Buddhist teaching both on the nature of reality, and the appearances of a Buddha.
Around 300 CE, the yogacara school systematized the prevalent ideas on the nature of the Buddha in the trikaya "three-body" doctrine.
According to this doctrine, buddhahood has three aspects:[3] Tulku Thondup states that dharmakaya must possess three great qualities:[4] According to Guang Xing, two main aspects of the Buddha can be seen in Mahāsāṃghika teachings: the true Buddha who is omniscient and omnipotent, and the manifested forms through which he liberates sentient beings through skillful means.
It appears also that the term’s usage in the sense of teaching is a later schema rather than being the early Buddhist common notions as generally understood.
[11] In a post-canonical Sri Lankan text called Saddharmaratnākaraya, a distinction is drawn between four different kāyas: the rūpakāya, dharmakāya, nimittakāya and suñyakāya.
[13] In a more unorthodox approach, Maryla Falk has made the argument that in the earliest form of Buddhism, a yogic path existed which involved the acquisition of a manomayakāya or dhammakāya and an amatakāya, in which the manomayakāya or dhammakāya refers to the attainment of the jhānas, and the amatakāya to the attainment of insight and the culmination of the path.
[14][15] Although Reynolds does not express agreement with Falk's entire theory, he does consider the idea of an earlier yogic strand worthy of investigation.
Furthermore, he points out that there are remarkable resemblances with interpretations that can be found in Yogāvacara texts, often called Tantric Theravada.
Basing itself on the Pali suttas and meditative experience, the tradition teaches that the dhammakaya is the eternal Buddha within all beings.
Paul Williams has commented that this view of Buddhism is similar to ideas found in the shentong teachings of the Jonang school of Tibet made famous by Dolpopa Sherab Gyaltsen.
[24]In the Lotus Sutra (Chapter 16: The Life Span of Thus Come One, sixth fascicle) the Buddha explains that he has always and will always exist to lead beings to their salvation.
"These terms are found in sutras such as the Lankavatara, Gandavyuha, Angulimaliya, Srimala, and the Mahaparinirvana, where they are used to describe the Buddha, the Truth Body (dharmakaya) and the Buddha-nature.
[26] Gyurme Dorje and Thupten Jinpa define "Buddha-body of Reality", which is a rendering of the Tibetan chos-sku and the Sanskrit dharmakāya, as: [T]he ultimate nature or essence of the enlightened mind [byang-chub sems], which is uncreated (skye-med), free from the limits of conceptual elaboration (spros-pa'i mtha'-bral), empty of inherent existence (rang-bzhin-gyis stong-pa), naturally radiant, beyond duality and spacious like the sky.
[31] Thondup and Talbott identify dharmakaya with the naked ("sky-clad"; Sanskrit: Digāmbara), unornamented, sky-blue Samantabhadra: In Nyingma icons, dharmakāya is symbolized by a naked, sky-coloured (light blue) male and female Buddha in union [Kāmamudrā], called Samantabhadra [and Samantabhadrī].
[32] The colour blue is an iconographic polysemic rendering of the mahābhūta element of the "pure light" of space (Sanskrit: आकाश ākāśa).
[33] The conceptually bridging and building poetic device of analogy, as an exemplar where dharmakaya is evocatively likened to sky and space, is a persistent and pervasive visual metaphor throughout the early Dzogchen and Nyingma literature and functions as a linkage and conduit between the 'conceptual' and 'conceivable' and the 'ineffable' and 'inconceivable' (Sanskrit: acintya).