This research is a qualitative study based on the Buddhist concept of Buddha-nature and focused on Theravāda and Mahāyāna Sūtras with three main objectives: 1) To study the Concept of Buddha-Nature in Theravāda Buddhism. 2) To study the Concept of Buddha-Nature in Mahāyāna Buddhism. 3) To compare the Buddha-Nature in Theravāda Buddhism and Mahāyāna Buddhism.
The study that addressed the first objective established the concept of Buddha-nature in Theravāda Buddhism. Although the concept of Buddha-nature appears in some other terms in short paragraphs of Theravāda Sūtras as “luminous mind”, “emptiness” and “purity”, those concepts emphasize the liberation of mind as the Buddha experienced. The study which addressed the second objective found that the concept of Buddha-nature with the terms such as “luminous mind”, “emptiness”, “purity” in Theravāda Buddhism are accepted and deployed widely in different forms by Mahāyāna Buddhism. All Mahāyāna Sūtras or the content of the whole Sūtras are surrounded by the concept of Buddha-nature. The Zen sect, Pure Land School aims at developing this concept through practice and experience to realize it. It is a core concept; it is the ultimate enlightenment and is the ultimate goal of practice in Mahāyāna Buddhism. The third objective revealed the similarities about pure mind, absolute tranquil essence, the ultimate reality (paramattha-sacca) of the concept of Buddha nature in Theravāda and Mahāyāna Buddhism and differences about realizing Buddha nature, the gradual enlightenment and sudden enlightenment, all beings have Buddha nature and propagating Buddha Nature of the two traditions.
Generally the essential Buddhism of both Theravāda and Mahāyāna is to practice to achieve a pure state of mind, to live with Buddha-nature so all defilements are absent, suffering ceases and the practitioner still lives in life but realizes all things for what they really are in the present reality.