Zen asserts, as do other schools in Mahāyāna Buddhism, that all sentient beings have Buddha-nature (Skt. Buddhadhātu, Tathāgatagarbha), the universal nature of transcendent wisdom (Skt. prajñā), and emphasizes that Buddha-nature is nothing other than the essential nature of the mind itself. The aim of Zen practice is to discover this Buddha-nature within each person, through meditation and practice of the Buddha’s teachings. The ultimate goal of this is to become a Completely Enlightened Buddha (Skt. Samyaksaṃbuddha). As a school of Mahāyāna Buddhism, Zen draws many of its basic driving concepts from that tradition, such as the bodhisattva ideal. Buddhas and bodhisattvas such as Amitābha, Avalokiteśvara, Mañjuśrī, Samantabhadra, and Kṣitigarbha are also venerated alongside Gautama Buddha.
The Zen tradition holds that in meditation practice, notions of doctrine and teachings necessitate the creation of various notions and appearances (Skt. saṃjñā; Ch. 相, xiāng) that obscure the transcendent wisdom of each being’s Buddha-nature. This process of rediscovery goes under various terms such as “introspection”, “a backward step”, “turning-about” or “turning the eye inward”. The importance of Zen’s non-reliance on written words is often misunderstood as being against the study of Buddhist texts. However, Zen is deeply rooted in the teachings and doctrines of Mahāyāna Buddhism. What the Zen tradition emphasizes is that enlightenment of the Buddha came not through intellectual reasoning, but rather through self-realization in Dharma practice and meditation. Therefore, it is held that it is primarily through Dharma practice and meditation that others may attain enlightenment and become buddhas as well.
In its beginnings in China, Zen primarily referred to the Mahāyāna sūtras and especially to the Laṅkāvatāra Sūtra. As a result, early masters of the Zen tradition were referred to as “Laṅkāvatāra masters”. Accounts recording the history of this early period are to be found in Records of the Laṅkāvatāra Masters (Ch. 楞伽師資記, Léngqié Shīzī Jì). Since the theoretical reference for the Zen was primarily the Laṅkāvatāra Sūtra, the Zen school had strong associations with this text. As the Laṅkāvatāra Sūtra teaches the doctrine of the “One Vehicle” (Skt. Ekayāna), the early Zen school was sometimes referred to as the “One Vehicle School”. In other early texts, the school that would later become known as Zen is sometimes even referred to as simply the “Laṅkāvatāra school” (Ch. 楞伽宗, Léngqié Zōng).
During the Tang Dynasty, the Zen school’s central text shifted to the Diamond Sūtra (Vajracchedikā Prajñāpāramitā Sūtra). Thereafter, the essential texts of the Zen school were often considered to be the Laṅkāvatāra Sūtra and the Diamond Sūtra. However, a review of the early historical documents and literature of early Zen masters clearly reveals that they were all well-versed in numerous Mahāyāna Buddhist sūtras. For example, in the Platform Sūtra of the Sixth Patriarch, Huineng cites and explains the Diamond Sūtra, the Lotus Sūtra (Saddharma Puṇḍarīka Sūtra), the Vimalakīrti Nirdeśa Sūtra, the Śūraṅgama Sūtra, and the Laṅkāvatāra Sūtra.
When Buddhism came to China, there were three divisions of training: the training in virtue and discipline in the precepts (Skt. śīla), the training in mind through meditation (Skt. dhyāna) to attain deep states of meditation (Skt. samādhi), and the training in the recorded teachings (Skt. Dharma). It was in this context that Buddhism entered into Chinese culture. Three types of teachers with expertise in each training practice developed: Vinaya masters specialized in all the rules of discipline for monks and nuns, Dhyāna masters specialized in the practice of meditation, and Dharma masters specialized in mastery of the Buddhist texts. Monasteries and practice centers were created that tended to focus on either the vinaya and training of monks or the teachings focused on one scripture or a small group of texts. Dhyāna (Ch. Chán) masters tended to practice in solitary hermitages, or to be associated with Vinaya training monasteries or the Dharma teaching centers. The later naming of the Zen school has its origins in this view of the threefold division of training.
At the beginning of the Tang Dynasty, by the time of the Fifth Patriarch Hongren (601–674), the Zen school had become well established as a separate school of Buddhism. Subsequently, the Zen tradition produced a rich corpus of written literature which has become a part of its practice and teaching. Among the earliest and most widely studied of the specifically Zen texts, dating back to at least the 9th century CE, is the Platform Sūtra of the Sixth Patriarch, attributed to Huineng. Others include the various collections of kōans and the Shōbōgenzō of Dōgen Zenji.
As the Zen school grew in China, the monastic discipline also became distinct, focusing on practice through all aspects of life. Temples began emphasizing labor and humility, expanding the training of Zen to include the mundane tasks of daily life. D.T. Suzuki wrote that aspects of this life are: a life of humility; a life of labor; a life of service; a life of prayer and gratitude; and a life of meditation. The Chinese Chán master Baizhang (720–814 CE) left behind a famous saying which had been the guiding principle of his life, “A day without work is a day without food”.