Prajna is known as the supreme，incomparable wisdom obtained through the realization of the unreality of all things. The Prajna doctrine is the core teaching of all Mahayana schools, just as the Vijnanakatra doctrine is more associated with the Theravada tradition. The Prajna learning began in the second or third century when Nagarjuna discovered the Prajna Sutras at the Snow Mountain Pagoda in North India and wrote the Maha-Prajnaparamitasastra [ta-chih-tu-luenn，大智度論] to explain and spread the ，Prajna doctrine. Kumarajiva carried the Prajna thought one step further by developing it into a practical Ch'an method at Kuan Ho. Under the heads of Meditation and Wisdom，Kumarajiva pointed out Thusness, Dharma Nature and Ultimate Reality as the three steps in the gradual realization of Prajna. Seng Chao [僧肇]，one of the chief disciples of Kumarajiva, developed the ideas further in three treatises：The Immutability of Things [物不遷論]，The Emptiness of the Unreal [不真空論] and Nirvana Is Beyond Knowing [涅槃無名論]. Thus, he turned Kumarajiva's ideas into specific steps of meditation and established the earliest meditation system in Mahayana, the Prajna Ch'an Method.
