The fundamental principle of Tendai may be called introspection (Kwanshin no hoho), but it is also a system of harmonization whereby an attempt is made to evolve something like harmony and order out of the bewildering chaos of the Buddhist Scriptures. Its teachings are divided into two great divisions or gates, the gate of teaching (Kyo) and the gate of meditation (Kwan), and it claims that a man can attain to Enlightenment by following either the teachings contained in the Scriptures or the practice of meditation and contemplation. It distinguishes three Vehicles instead of two: the Hinayana (or Shojo), the Apparent or Quasi-Mahayana of the Jodo and Indian sects (Gondaijo), and the true Mahayana of the sects which originated in China--Zen, Shingon, Kegon, and itself (Jitsudaijo).

It embraced the whole collection of the Mahayana books, which it divided into five periods. S'akyamuni, it was said, had begun his ministry by preaching in heaven, to angels and men, the transcendent doctrines of the Kegon. These being too hard for ordinary, sinful men to comprehend, he had descended to Benares with the practical teaching of the Agon Scriptures. As times rolled on the teachings had been "developed" (vaipulya) in the Hodo books, as the next class were called. From development to wisdom (prajna) was the next step; from wisdom to the consummated perfection of the Sad-dharma pundarika Sutra was the natural conclusion. Thus the doctrines of S'akyamuni were 84,000 in number

beginning with extreme simplicity and ending in the clouds of mysticism. In the delivery of these many doctrines Shaka had used many ways of teaching: ton, or suddenness, letting the truth burst with full brilliancy on the mind of his hearers; zen, or gradual advance from strength to strength; himitsu, or esoteric symbolism; fujo, or parabolic uncertainty. He had adapted his sermons to all hearers, and had so contrived that in one and the same sermon the same words had conveyed Hinayana doctrines to some hearers and Mahayana to others who were able to bear it. He had indeed become "all things to all men."

The Tendai system, which embraced all, comprised many things which were not Buddhist at all. Its doctrine of sho aku no homon, or inherent evil, is dualistic; it asserts that in Shinnyo, which is the pantheistic god, there is an evil principle as well as a good, that the two are equal in duration and power. Manichaeans and Magi both held that doctrine, but it was scarcely a Buddhist principle. It must have been a very difficult task to get doctrines so mutually antagonistic as those of the Zen and Ado to live side by side in the same religious household.

But the main thing that Saicho wanted was spiritual and ecclesiastical authority. This the Chinese Tientai seems to have had little hesitation about granting, and Saicho was soon back in Japan, with a native episcopate in his own hands.