In A.D. 805, two Japanese pilgrims went to China, and received orthodox training.  With twenty others, they brought the Ten-dai doctrines into Japan.  During this century, other Japanese disciples of the same sect crossed the seas to study at Mount Tien Tai.  On coming back to Japan they propagated the various shades of doctrine, so that this main sect has many branches.  It was chiefly through these pilgrims from the West that the Sanskrit letters, writing and literature were imported.  In our day, evidences of Sanskrit learning, long since neglected and forgotten, are seen chiefly in the graveyards and in charms and amulets.

Although the philosophical doctrines of Ten-dai are much the same as those of the Ke-gon sect, being based on pantheistic realism, and teaching that the Buddha-tathata or Nature absolute is the essence of all things, yet the Ten-dai school has striking and peculiar features of its own.  Instead of taking some particular book or books in the canon, shastra, or sutra, selection or collection, as a basis, the Chinese monk Chi-sha first mastered, and then digested the whole canon.  Then selecting certain doctrines for emphasis he supported them by a wide range of quotation, professing to give the gist of the pure teachings of Gautama rather than those of his disciples.  In practice, however, the Saddharma Pundarika is the book most honored by this sect; the other sutras being employed mainly as commentary.  Furthermore, this sect makes as strenuous a claim for the true apostolical succession from the Founder, as do the other sects.

The teachers of Ten-dai doctrine must fully estimate character and ability in their pupils, and so apportion instruction.  In this respect and in not a few others, they are like the disciples of Loyola, and have properly been called the Jesuits of Buddhism.  They are ascetics, and teach that spiritual insight is possible only through prolonged thought.  Their purpose is to recognize the Buddha, in all the forms he has assumed in order to save mankind.  Nevertheless, the highest truths are incomprehensible except to those who have already attained to Buddha-hood.[19] In contrast to the Nichirenites, who give an emotional and ultra-concrete interpretation and expression to the great sutra, Hokke Ki[=o], the Ten-dai teachers are excessively philosophical and intellectual.

In its history the Ten-dai sect has followed out its logic.  Being realistic in pantheism, it reverences not only Gautama the historic Buddha, but also, large numbers of the Hindu deities, the group of idols called Jiz[=o], the god Fudo, and Kuannon the god or goddess of mercy, under his or her protean forms.  In its early history this sect welcomed to its pantheon the Shint[=o] gods, who, according to the scheme of Riy[=o]bu Shint[=o], were declared to be avatars or manifestations of Buddha.  The three sub-sects still differ in their worship of the avatars selected as supreme deities, but their philosophy enables them to sweep in the Buddhas of every age and clime, name and nation.  Many other personifications are found honored in the Ten-dai temples.  At the gateways may usually be seen the colossal painted and hideous images of the two Devas or kings (Ni-O).  These worthies are none other than Indra and Brahma of the old Vedic mythology.