Religion in the Medieval Period
Shinto vs. Buddhism?
Two major Japanese perspectives that provide an overview of Japanese religion are those of Shinto and Buddhism. Although each tradition includes a wide range of attitudes and commitments, for the purpose of our discussion we can assume two contrasting “voices” that highlight the problem of conceptualizing Japanese religion. Generally, Shinto priests and scholars in modern times have viewed Shinto from the vantage point of the post-Meiji-era when Shinto was legally isolated from Buddhism and became much more highly organized as a distinct institutional “religion” than in pre-Meiji times. From their viewpoint, Shinto is seen as the “unique” Japanese religious heritage, with direct continuity from prehistoric times down to the present, temporarily dominated by foreign traditions such as Buddhism, but throughout history representing the “authentic” national spiritual heritage. In this perception, Shinto’s modern identity and more organized character have been considered as present in much earlier times; however, even more important, Shinto is perceived not so much as a formal religious institution, but rather as a permanent and indelible feature of Japanese culture and religion. Therefore, following this line of reasoning, because the kami created the Japanese islands and the kami are the source of Japanese people and all life (such as the all-important rice), implicitly or unconsciously all Japanese are considered to “naturally” [i.e. “essentially”] be a part of Shinto.

Generally, Buddhist priests and scholars in modern times share with Shinto priests and scholars a post-Meiji conception of Shinto and Buddhism as two separate religions. But there is considerable divergence between the two groups of priests and scholars and their notions of the differences and relationships between the respective traditions. Buddhism’s modern viewpoint is shaped even more by the perception of religion and Buddhism gained from sophisticated Buddhist studies focusing not only on Buddhism as a philosophical tradition but also on each Buddhist sect as a separate ecclesiastical and doctrinal heritage. In other words, Buddhism and religion in general are viewed as highly organized institutions with elaborate doctrine and ecclesiastical structures. From this vantage point, Buddhist spokespeople have often looked down on early Shinto as a “primitive” religion without a complex organizational form and as holding implicit and uncritical “animistic” beliefs in spirits rather than explicit bodies of codified doctrine and systematic philosophy. In fact, from the viewpoint of Buddhism and a highly formal view of religion, it has been argued that Shinto did not exist as a full-fledged religion until quite recently, and that Buddhism provided the main Japanese religious heritage from ancient and medieval times down to about the Meiji period.

These two polemical, almost contradictory, viewpoints present us with a dilemma. Should we see Shinto as the implicit or unconscious spiritual heritage of the Japanese people, in other words, the unique religious tradition of the Japanese nation? Or should we consider Shinto a loose set of primitive beliefs not organized as a religion until the nineteenth century? Before we make a choice between these two alternatives, we should recognize a hidden assumption within this critical view of Shinto. If the critique of “Shinto” as a concept is that it is not highly organized, but rather a loose set of animistic or “primitive” beliefs, does this mean that the concept of “Buddhism” is a set of formally organized institutions with abstract doctrines?

We need only return to the Nara period to remember that Buddhism, for all its institutional and doctrinal complexity, was accepted and practiced for various magical techniques and worldly benefits. Throughout its history in Japan, down to the present, Buddhism has been received, believed, and invoked by people mainly for its practical benefits, not for its institutional strength or doctrinal superiority. This makes the choices more complex: we can view Japanese religion through Shinto theory or Buddhist doctrine; turning this upside down, we could view Japanese religion through Shinto practice or Buddhist practice. (Japanese Religion, 116-7)
Two Good Lessons
There are two good lessons from this consideration of how to interpret Shinto, something to keep in mind throughout our consideration of Japanese religion. One lesson is to remember that our contemporary notion of religion as an area of life separate from other areas, and as discrete traditions rather compartmentalized one from another, was not present in premodern Japan. Another lesson is that whenever we view Shinto, or Buddhism, or Japanese religion, we should ask ourselves what viewpoint we are using, and the advantages and limitations of that viewpoint. (Japanese Religion, 118)
A Buddhist Transformation of Shinto...
...Or a Shinto Transformation of Buddhism?
In summary, on the formal and institutional level Buddhism seemed to overwhelm Shinto, but on the informal and local level Buddhism never superseded Shinto. In fact, Shinto’s appropriation of Buddhist symbols and rites helped enhance Buddhism’s popular appeal. As Buddhism was accepted by the Japanese people and they were converted as Buddhists, Buddhism itself was transformed into a Japanese religious reality. It can be argued that although Buddhism seemed to triumph on the surface, the religious life of Shinto persevered — even within Buddhist forms, beneath the surface.

One Buddhologist, writing mainly about Kamakura Buddhism, has made a point that applies generally to Buddhism in the premodern period: “the truly unique character of Japanese Buddhism seems to have been the institutional, doctrinal, and ritual integration of Buddhism and Shinto.” (Japanese Religion, 119)

To understand Buddhist-Shinto syncretism in the ensuing centuries, it is important to notice how Shotoku’s and Shomu’s strategies for synthesis differed. Shotoku’s Seventeen-Article Constitution synthesized Buddhism and Confucianism by establishing an external relation between the two. Each tradition retained its identity and independence by being assigned a different domain of authority. ... [The] complementarity allows the Confucian aspect to remain completely Confucian and the Buddhist aspect completely Buddhist. The integrity of each tradition was not penetrated by the other tradition, and their interface was negotiated by giving each its own sphere of influence. It was as if Shotoku was working out a contract or treaty between the two imported traditions.

When Emperor Shomu melded Buddhism with Shinto a century and a half later, however, his synthesis nurtured an internal relation between the two. He had discovered an overlap in the symbol systems of the two traditions: the spirituality of the sun. For Shinto this spirituality lay in the sun kami, Amaterasu. This was especially important to Shomu because Kojiki  and Nihonshoki (written just a few decades earlier) had formally promulgated the familial connection between Amaterasu and the imperial line. For the Buddhist side of the equation, Shomu knew that the Kegon school, one of the most prominent Buddhist groups in Nara, considered the Sun Buddha to be the basic spiritual principle of the whole cosmos. ...

As we have seen, when Shomu built Nara’s Great Temple to the East (Todai-ji) in the mid-eight century, he assigned the temple to the Kegon school, cast the monumental bronze image of the Great Sun Buddha, and took for himself a lay ordination name using a variant appellation for the same Buddha. ... In effect, he made himself a holographic entry point for the intersection of the two traditions. Through such a tactic he could be the chief priest of Shinto — a direct descendant of the sun kami — while simultaneously being an ordained Buddhist layman. (SWH, 93-4)
Perhaps the best way to introduce medieval Shinto is to discuss it in terms of the traditions that influenced it. Although Buddhism was not the only influential tradition, it was undoubtedly the most important. The Buddhist theory of honji-suijaku (“original substance manifests traces”) pervaded practically the whole of Shinto. The theory of honji-suijaku, transmitted from China to Japan, became the theoretical foundation for considering Japanese kami as “manifest traces” (suijaku) or counterparts of the “original substance” (honji) of particular Buddhas and bodhisattvas. For example, as early as the Nara period, Hachiman was considered both a kami and a bodhisattva without a clear distinction of Shinto or Buddhist identity. In later periods almost every Shinto shrine considered its enshrined kami as the counterpart of some Buddha or Buddhist divinity. It was customary to enshrine statues of these Buddhist counterparts in Shinto shrines, and this practice further encouraged the interaction of Buddhist and Shinto priests. (Japanese Religion, 120-1)
The honji suijaku theory was an extension of the idea that the universe is really the activity of the Cosmic Buddha and that everything we think of as the cosmos is only the symbolic expression of this activity. Hence all the various buddhas and bodhisattvas are ultimately symbolic expressions, almost like emanations, of the single Cosmic Buddha. For esoteric Buddhism, the “ground of reality” (honji) is Buddha-filled; but this ground has “traces” (suijaku) giving us the kami-filled world of Shinto belief. By this reasoning, the various kami are surface manifestations of buddhas existing on a deeper level of reality (which are themselves emanating from the Cosmic Buddha).
The honji suijaku theory was, therefore, an explanation of how a universal (Buddhist) reality could become localized as a Japanese (Shinto) reality. This is fully in accord with the more traditional esoteric Buddhist belief that the entire cosmos is the Cosmic Buddha and the world as we know it is the manifestation of the activities of this Buddha. Esoteric Buddhists use mandalas to portray how all buddhas emanate from the Cosmic Buddha (usually considered Dainichi).
In accord with the honji suijaku theory, so-called suijaku art developed similar mandalas with kami portrayed in place of the buddhas. This usually meant that Amaterasu replaced Dainichi at the mandala’s center, suggesting in effect that all the kami emanated from her. In short: esoteric Buddhist theory tended to fuse with traditional Shinto beliefs by intellectually assimilating it, making it a manifestation — but only one manifestation — within the broader Buddhist worldview. (SWH, 98)

Medieval Shinto
The Tendai and Shingon Traditions
One significant system of borrowing between Shinto and Buddhism was at Mount Hiei, the mountain headquarters of Tendai. (The basic mode of borrowing was similar at Mount Koya, the mountain headquarters of Shingon.) In the Heian period, Shinto shrines and Buddhist temples stood side by side, and priests of Shinto and Buddhism sometimes participated in each other’s rites. The founders of the two Buddhist sects, Dengyo Daishi and Kobo Daishi, thought it only natural that shrines should be erected to honor the local kami of their respective mountains. Gradually there emerged at each locale individual forms of thought and practice that related the Shinto kami and Buddhist doctrine. Because the Tendai headquarters was modeled after the Chinese mountain headquarters by the same name (T’ien-t’ai in Chinese), the Tendai scholars had a Chinese precedent to follow in recognizing local deities. The collective name for the local Japanese kami and Buddhas at Mount Hiei, adopted from the Chinese, was “mountain king” (pronounced “Sanno” in Japanese); they were worshiped at the Shinto shrine Hie Taisha at the foot of Mount Hiei. “Grounded in both local and elite native traditions, the Shinto shrines of Hiei came to be seen as the protectors of the Buddhist institutions of Mount Hiei with which they gradually evolved systematic relations at all levels of existence. (Japanese Religion, 121-2)
The theoretical foundation of the system, according to Tendai, was found in the highly revered Lotus Sutra. This text states that all the Buddhas that come into the world are only “one reality” (ichi jitsu) — the Tendai concept of an absolute reality behind the whole universe. The theory was used to argue that the various kami are Japanese historical appearances that correspond to Buddhist divinities, all of which are subsumed in the “one reality.” This form of Shinto was called either “Sanno Shinto” or “Ichi-jitsu Shinto.” The honji-suijaku theory set up a general framework of correspondences between kami and Buddhist divinities; Ichi-jitsu Shinto developed a particular theory of correspondences based on Tendai teaching. (Japanese Religion, 122)

In the same vein, we can see Shinto absorbing the Shingon notion that the whole world can best be understood through two mandala. The symbolic pictures of the cosmos represent the bipolar character of existence evident in the mutually opposing forces of matter-mind, male-female, and dynamic expression-static potential. Within this ideological framework, Shinto priests could coordinate Japanese kami and Buddhist divinities, for they could place some kami within the womb mandala and other kami within the diamond mandala. Because this style of Shinto emphasized the two mandala of Shingon, it was called Ryobu Shinto. Ryobu means “two parts” or “dual,” and sometimes Ryobu Shinto has been called “Dual Shinto.” A famous example of the rationale of Ryobu Shinto is found at the Ise Shrines, the most venerated shrines in Japan. Amaterasu, the Sun Goddess and ancestress of the imperial family, is enshrined at Ise. In later times the Sun Goddess came to be equated with the Sun Buddha (Dainichi or Birushana or Vairocana) of the Mahavairocana Sutra, which is the main scripture of Shingon. The Ise Shrines, which include the Inner Shrine and Outer Shrine, came to be considered representations of the two mandala of Shingon. (Japanese Religion, 122-3)
From the very moment when Shinto arose, we see a general picture of Shinto appropriating as much as it could of the continental traditions. But Shinto was not a passive recipient of these influences; rather, it actively adapted the new elements. The apparent reason for this appropriation and adaptation was to strengthen and organize Shinto. Then, as Shinto became more self-confident, it attempted to reassert its distinctiveness and superiority.
       A good example of Shinto adaptation is the Yui-itsu (or Yui-ichi) school of Shinto. This school set forth a reverse honji-suijaku theory (han-honji-suijaku), making the Japanese kami the “original substance” (honji) and the Buddhist divinity the “manifest trace” (suijaku) and giving the superior position to the Japanese kami. The Yui-itsu school of Shinto, sometimes named after the Urabe or Yoshida family, developed a comprehensive pantheistic system on this basic principle, making Shinto into an all-embracing philosophy and religion. The Yui-itsu school and other Shinto scholars used similar schemes to try to set themselves apart from Buddhism, Confucianism, and Taoism. However, from our historical vantage point we can see that they could not escape from the received influence. The pantheistic system was pervaded by the very Buddhist influence that Shinto scholars were trying to escape. Nevertheless, these movements are important for understanding the growing Shinto concern to “purify” itself and to regain its former position of glory. (Japanese Religion, 124)