This branch of Buddhism is said to have been founded in India about A.D. 200, by a saint who made the discovery of an iron pagoda inhabited by the holy one, Vagrasattva, who communicated the exact doctrine to those who have handed it down through the Hindoo and Chinese patriarchs.  The books or scriptures of this sect are in three sutras; yet the essential point in them is the Mandala or the circle of the Two Parts, or in Japanese Riy[=o]bu.  Introduced into China, A.D. 720, it is known as the Yoga-chara school.

K[=o]b[=o] finding a Chinese worm, made a Japanese dragon, able to swallow a national religion.  In the act of deglutition and the long process of the digestion of Shint[=o], Japanese Buddhism became something different from every other form of the faith in Asia.  Noted above all previous developments of Buddhism for its pantheistic tendencies, the Shingon sect could recognize in any Shint[=o] god, demi-god, hero, or being, the avatar in a previous stage of existence of some Buddhist being of corresponding grade.

For example,[24] Amateras[)u] or Ten-Sh[=o]-Dai-Jin, the sun-goddess, becomes Dai Nichi Ni[=o]rai or Amida, whose colossal effigies stand in the bronze images Dai Butsu at Nara, Ki[=o]to and Kamakura.  Ojin, the god of war, became Hachiman Dai Bosatsu, or the great Bodhisattva of the Eight Banners.  Adopted as their patron by the fighting Genji or Minamoto warriors of mediaeval times, the Buddhists could not well afford to have this popular deity outside their pantheon.

For each of the thirty days of the month, a Bodhisattva, or in Japanese pronunciation Bosatsu, was appointed.  Each of these Bodhisattvas became a Dai Mi[=o] Jin or Great Enlightened Spirit, and was represented as an avatar in Japan of Buddha in the previous ages, when the Japanese were not yet prepared to receive the holy law of Buddhism.

Where there were not enough Dai Mi[=o] Jin already existing in native traditions to fill out the number required by the new scheme, new titles were invented.  One of these was Ten-jin, Heavenly being or spirit.  The famous statesman and scholar of the tenth century, Sugawara Michizane, was posthumously named Tenjin, and is even to this day worshipped by many children of Japan as he was formerly for a thousand years by nearly all of them, as the divine patron of letters.  Kompira, Benten and other popular deities, often considered as properly belonging to Shint[=o], “are evidently the offspring of Buddhist priestly ingenuity."[25] Out of the eight millions or so of native gods, several hundred were catalogued under the general term Gon-gen, or temporary manifestations of Buddha.  In this list are to be found not only the heroes of local tradition, but even deified forces of nature, such as wind and fire.  The custom of making gods of great men after their death, thus begun on a large scale by K[=o]b[=o], has gone on for centuries.  Iyeyas[)u], the political unifier of Japan, shines as a star of the first magnitude in the heavens of the Riy[=o]bu system, under the mime of T[=o]-sh[=o]-g[=u], or Great Light of the East.  The common people speak of him as Gon-gen Sama, the latter word being an honorary form of address for all beings from a baby to a Bosatsu.