The nature of the opposition which the ancient religion of Japan could offer to the introduction of any hostile alien creed, should now be obvious. The family being founded upon ancestor-worship, the commune being regulated by ancestor-worship, the clan-group or tribe being governed by ancestor-worship, and the Supreme Ruler being at once the high-priest and deity of an ancestral cult which united all the other cults in one common tradition, it must be evident that the promulgation of any religion essentially opposed to Shinto would have signified nothing less than an attack upon the whole system of society. Considering these circumstances, it may well seem strange that Buddhism should have succeeded, after some preliminary struggles (which included one bloody battle), in getting itself accepted as a second national faith. But although the original Buddhist doctrine was essentially in disaccord with Shinto beliefs, Buddhism had learned in India, in China, in Korea, and in divers adjacent countries, how to meet the spiritual needs of peoples maintaining a persistent ancestor-worship. Intolerance of ancestor-worship would have long, ago resulted in the extinction of Buddhism; for its vast conquests have all been made among ancestor-worshipping races. Neither in India nor in China nor in Korea, - neither in Siam nor Burmah nor Annam, - did it attempt to extinguish ancestor-worship, Everywhere it made itself accepted as an ally, nowhere as an enemy, of social custom. In Japan it adopted the same policy which had secured its progress on the continent; and in order to form any clear conception of Japanese religious conditions, this fact must be kept in mind.
As the oldest extant Japanese texts - with the probable exception of some Shinto rituals - date from the eighth century, it is only possible to surmise the social conditions of that earlier epoch in which there was no form of religion but ancestor-worship. Only by imagining the absence of all Chinese and Korean influences, can we form some vague idea of the state of things which existed during the so-called Age of the Gods, - and it is difficult to decide at what period these influences began to operate. Confucianism appears to have preceded Buddhism by a considerable interval; and its progress, as an organizing power, was much more rapid. Buddhism was first introduced from Korea, about 552 A.D.; but the mission accomplished little. By the end of the eighth century the whole fabric of Japanese administration had been reorganized upon the Chinese plan, under Confucian influence; but it was not until well into the ninth century that Buddhism really began to spread throughout the country. Eventually it over-shadowed the national life, and coloured all the national thought. Yet the extraordinary conservatism of the ancient ancestor-cult - its inherent power of resisting fusion - was exemplified by the readiness with which the two religions fell apart on the disestablishment of Buddhism in 1871. After having been literally overlaid by Buddhism for nearly a thousand years, Shinto immediately reassumed its archaic simplicity, and reestablished the unaltered forms of its earliest rites.
But the attempt of Buddhism to absorb Shinto seemed at one period to have almost succeeded. The method of the absorption is said to have been devised, about the year 800, by the famous founder of the Shingon sect, Kukai or "Kobodaishi" (as he is popularly called), who first declared the higher Shinto gods to be incarnations of various Buddhas. But in this matter, of course, Kobodaishi was merely following precedents of Buddhist policy. Under the name of Ryobu-Shinto,* the new compound of Shinto and Buddhism obtained imperial approval and support. [*The term "Ryobu" signifies "two-departments" or "two religions."] Thereafter, in hundreds of places, the two religions were domiciled within the same precinct - sometimes even within the same building: they seemed to have been veritably amalgamated. And nevertheless there was no real fusion; - after ten centuries of such contact they separated again, as lightly as if they had never touched. It was only in the domestic form of the ancestor-cult that Buddhism really affected permanent modifications; yet even these were neither fundamental nor universal. In certain provinces they were not made; and almost everywhere a considerable part of the population preferred to follow the Shinto form of the ancestor-cult. Yet another large class of persons, converts to Buddhism, continued to profess the older creed as well; and, while practising their ancestor-worship according to the Buddhist rite, maintained separately also the domestic worship of the elder gods. In most Japanese houses to-day, the "god-shelf" and the Buddhist shrine can both be found; both cults being maintained under the same roof.* ... But I am mentioning these facts only as illustrating the conservative vitality of Shinto, not as indicating any weakness in the Buddhist propaganda. Unquestionably the influence which Buddhism exerted upon Japanese civilization was immense, profound, multiform, incalculable; and the only wonder is that it should not have been able to stifle Shinto forever. To state, as various writers have carelessly stated, that Buddhism became the popular religion, while Shinto remained the official religion, is altogether misleading. As a matter of fact Buddhism became as much an official religion as Shinto itself, and influenced the lives of the highest classes not less than the lives of the poor. It made monks of Emperors, and nuns of their daughters; it decided the conduct of rulers, the nature of decrees, and the administration of laws. In every community the Buddhist parish-priest was a public official as well as a spiritual teacher: he kept the parish register, and made report to the authorities upon local matters of importance.