Kūkai's family were aristocratic, and being a gifted child he was sent to university were he studied the Chinese_classics, became acquainted with Tantric_Buddhism. In particular he had discovered the Dainichikyo, or Maha Vairochana Sutra. However he was unable to a suitable teacher to explain it to him. In 804 he travelled managed to be included in a diplomatic mission to China, perhaps with the help of the Emperor Kanmu. In Ch'ang-an he studied Sanskrit and met his teacher Hui-kuo who gave him tantric initiation and taught him the esoteric doctrines contained in the Dainichikyo. Hui-Kuo decided to make Kūkai his successor, but asked him to return to Japan and teach the esoteric doctrines there for the benefit of the Japanese people. He returned to Japan with many scriptures and art objects.
Kūkai returned to a new emperor, Heizei, who showed little interest in Kūkai or his new teachings. The Tendai School run by Saicho was very popular and for a while eclipsed Kukai. Later however they assimilated many Shingon doctrines, and Saicho even approached Kukai to borrow scriptures that he had obtained in China.
Kūkai's main contribution to Buddhist thought was in synthesising all the existing teachings into a coherent whole. Over more than 1000 years Buddhist teachings had multiplied enormously, and many seemingly contradictory teachings were available. Kūkai created a hierarchical approach to spiritual practice which included Confucianism and Daoism as lower stages on the path - this was published in 830 as Jujushinron (Ten Stages of Mind Development) . He placed the Mahavairocana Sutra (actually an early Tantric text) at the pinnacle of teachings. Shingon is stronly influenced by the Tathāgatagarbha Doctrine, also known as 'Buddha Nature' which says that all beings are inherently pure from the very beginning. The highest attainment according to Shingon is the union of the individual's mind and body with the mind and body of the Dharmakaya Buddha, Mahavairochana.
Kūkai is famous as a calligrapher, engineer and is said to have invented (on the model of Sanskrit) kana, the syllabary in which, in combination with Chinese characters (Kanji) the Japanese language is written. His religious writing, some 50 works, expound the esoteric Shingon doctrine, of which the major ones have been translated into English by Hakeda (see below). Kūkai is also said to have written the iroha, one of the most famous poems in Japanese. In the 1100’s we begin to see also mentions of Kukai as the father of nanshoku, or male love. He is alleged to have learned about male love in China.
In 816CE he founded the Kongobuji monastery on Mount_Koya which has been at the center of Shingon Buddhism ever since. Mount Koya is still a center of pilgrimage, and there is a folk belief that Kūkai, who is buried there, is not dead but in deep meditation and will one day rise again. Mount Koya also was synonymous with shudo (the way of the young, the samurai tradition of male love) in the literary tradition of Japan. The title Kobo Daishi, 'Great teacher from Kobo', was granted posthumously.
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