When I first visited Japan as a college student many years ago, I came for the explicit purpose of studying Buddhism. Like many of my fellow travelers, I was introduced to Japanese Buddhism through the writing of mid-century American poets such as Allen Ginsberg, Gary Snyder, and Jack Kerouac. I chose a study abroad program that allowed foreign students to study at Buddhist temples, because I wanted to experience the spiritual adventures described in English-language literature on Buddhism. I expected to find austere mountain retreats filled with meditating monks who only paused from their pursuits toward enlightenment to craft elegant flower arrangements or compose enigmatic haiku. What I found was anything but the romanticized tales of American literature.

At a temple near the foothills of Mount Hiei, just to the northeast of Kyoto, we awoke at sunrise to join a dozen or so monks dressed in multicolored robes and reciting a series of chants that turned out to be scriptures. We then moved on to stay at another temple on Mount Koya to the south, where we participated in elaborate rituals featuring wrathful deities, fire, and rhythmic incantations. What were we chanting? I was curious to know what this all meant.

As I later discovered, both mountains are home to schools of esoteric Buddhism. These mountaintop monasteries were established in the early 9th century CE as training centers where clergy throughout Japan could study newly imported texts and their ritual applications. It is unclear what exactly this training consisted of during the early centuries, but learning the proper recitation of incantations called dharanis and mantras was certainly its primary objective. However, what exactly made these practices “esoteric” and how they were thought to differ from traditional Mahayana Buddhism are difficult questions to answer.

Like tantra and vajrayana in the Buddhist traditions of Central Asia, esoteric Buddhism in Japan is sometimes called the completion or fulfillment of the Buddha’s teachings. A millennium of wrangling among Buddhist scholastics and modern scholars has concluded that the esoteric teachings were not preached by the historical Shakyamuni Buddha during his 80 years of life in this world. Among their adherents, however, they are seen to be the timeless and ultimate truth of the dharma that caused Shakyamuni’s awakening to buddhahood in the first place. Therefore, those who cultivate these esoteric teachings have direct access to the very source of the Buddha’s enlightenment. If we put aside the particulars of such sectarian polemics, however, and explore how esoteric Buddhism has been discussed over the centuries, we discover a much more multivalent meaning to this arcane, although influential, tradition within Japanese Buddhism.

The English word esoteric originates from Greek, meaning “internal” or “inner.” The Sino-Japanese ideograph commonly translated as “esoteric Buddhism,” literally means “secret teachings.” We can generally define this form of Buddhism as a teaching of the Buddha that is either a secret to be discovered in the mind of the practitioner or knowledge limited to an elite group of practitioners. The basic etymological definition of the word, however, sheds very little light on the actual content and details of these so-called secret teachings, especially if we take into consideration the fact that the term “esoteric Buddhism” has come to denote several overlapping traditions, practices, and doctrines in Japanese Buddhism.

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Similar to classification systems of tantra in the Indo-Tibetan tradition, esoteric Buddhism in Japan denotes a class of scripture. Although the term tantra rarely appears in East Asian sources, many of the texts utilized in Japan are Chinese translations of early tantras. For instance, the Sarva-tathagata-tattva-samgraha, the primary source for the ritual system in Japanese esoteric Buddhism, was a seminal yoga tantra that still plays an important role in Nepali Buddhism. But this is where the similarities between Central and East Asian Buddhism end, and one must take caution not to assume a historical continuity between these traditions. While the early tantras gave way to the more systematic and detailed rites of the Guhyasamaja Tantra and Hevajra Tantra in India and Tibet, these textual and ritual traditions made no impact on East Asian Buddhism. Rather than devising a system of tantra distinct from the Mahayana sutras, esoteric Buddhist scholastics were mostly concerned with how newly translated texts such as the Sarva-tathagata-tattva-samgraha, Mahavairocana Sutra, Susiddhikara Sutra, and their respective ritual manuals compared with the teachings of older sutras, particularly the Lotus and the Mahaparinirvana.

Esoteric Buddhism can also be identified by a specific set of rituals that evolved out of these scriptures. The fourfold initiation rite (shido kegyo), for instance, is a series of incantation practices and rites involving mandalas, culminating in a fire ritual (goma, from Sanskrit homa); there are also other rites to produce worldly benefits such as rainmaking or healing. (By the late 12th century, such rites had become pervasive among clergy in Japan, whose livelihoods often relied on their perform-ance of these rituals.) Another kind of rite—the consecration rites called abhisheka—is also a staple of esoteric Buddhism. The imperial court even took part in special consecration rites that employed esoteric imagery, such as mandalas, and the recitation of mantras, and monastic centers and their clergy competed for imperial favor by providing such ritual services.

The ritual lineage was an important component of medieval esoteric Buddhism, perhaps more important than the rituals themselves. Ritual training systems varied according to lineage, and the affiliation of a monk with a particular temple and master was essential to the preservation of a given style of rite. The transmission of ritual protocols for mantras, the hand gestures known as mudras, and the procedures of a rite were transmitted secretly from master to disciple, which kept the correct performance of a rite secret as well. However, lineage and secrecy have long been important issues in East Asian Buddhism. The rites in esoteric Buddhism may have added new components based on recently translated sources, but the emphasis on orthodox lineage was nothing new or particularly esoteric.

Rhetoric should also be considered a part of any definition of esoteric Buddhism. Calling one’s own tradition “esoteric” and its central teachings “secret” is, of course, a polemical assertion. The term “secret teachings” implies a superior and elite knowledge. This knowledge is contrasted with a lesser “exoteric” form of the teaching, which is simpler and adapted for less advanced practitioners. The phrase “exo-esoteric Buddhism” is a case in point. By the 11th century, some esoteric schools began distinguishing themselves from others by declaring that only they had received transmission into the truly secret teachings of the Buddha. The other schools, it was claimed, also expounded the secret teachings, but still relied on an exoteric interpretation to explain them. The use of the pejorative “exo-esoteric Buddhism” was intended to elevate one’s own school over the other forms of esoteric Buddhism. In other words, to claim that one’s own tradition is esoteric is to assert authority over a superior lineage and knowledge of the teachings that is not necessarily accessible to the average practitioner.

Despite its polemical overtones, there is still a doctrinal basis to the notion of a secret teaching. The defining element of esoteric Buddhism in Japan is the claim that an initiate into the tradition can achieve liberation as a Buddha in this world and in his or her current physical body by realizing the secret teachings of the Buddha. The method for accomplishing this feat is called the cultivation of the three secret activities (sanmitsu gyo).

It is a common misconception that this doctrine originated with the esoteric sutras and was primarily a Japanese innovation. Actually, it can be found in Chinese Buddhism as early as the 3rd century, and by the time these texts were translated in the late 7th and 8th centuries, the doctrine of the three secret activities was already a topic frequently discussed among Chinese Buddhist intellectuals.

The concept of the three secret activities was based on a correlation between the three sources of karmic production in sentient beings—namely body, speech, and mind—and those same functions in the Buddha. Regulating these karmic actions has always been central to codes of conduct for monastics and lay practitioners alike. For example, the purpose of the ten lay precepts in Mahayana Buddhism is to instruct members of the Buddhist community in proper conduct regarding the karmic effects of their bodily, verbal, and mental actions. Prohibitions against killing, stealing, and engaging in sexual misconduct govern bodily actions that inevitably have negative karmic consequences. Restrictions on lying, slander, divisive language, and flattery allow the practitioner to cultivate wholesome speech. Ethical guidelines for eradicating greed, anger, and false views purify one’s mental state and eventually lead to liberation from such negative karmic results. Once the Mahayana practitioner ceases to commit these negative actions and instead cultivates wholesome bodily, linguistic, and mental activities, he or she will achieve a favorable rebirth and advance on the path toward buddhahood.

From early on in East Asian Buddhism, it was assumed that the Buddha must also possess these three activities. After all, if the Buddha spoke the sermons recorded in the sutras, he must have had the ability to speak. He also had a physical form, which is represented in numerous statues, drawings, and literary accounts detailing the distinctive marks of a buddha, so he clearly had bodily actions. And according to scriptures such as the Lotus Sutra, the Buddha teaches in response to the needs of sentient beings, so he must have some kind of mental activity in order to perceive these needs. However, a buddha, by definition, has extinguished all negative karmic output and therefore has purified the three activities. Because these pure activities are inconceivable to non-buddhas, they are called “secret.”

The claim that the Buddha possesses three karmic activities in a similar fashion to sentient beings was pervasive throughout Chinese and Japanese Buddhism. But the esoteric tradition differs from the mainstream Mahayana interpretation in its procedure for realizing these activities. To the question “How exactly can unenlightened sentient beings comprehend the rarified actions of the Buddha?” the obvious answer is that only someone who has experienced awakening knows what it is like to become a buddha. In the Mahayana schools, this process is explained in abstract terms such as “realizing the characteristics of thusness,” the “perfect interfusion of all existence,” or simply as “inconceivable.” The expedited path to liberation in esoteric Buddhism, however, is premised on the possibility of cultivating the three secret activities through a ritualized union with the Buddha, achieved by mimicking the body, speech, and mind of the Buddha.

By assuming the posture of a buddha and emulating its mudras, the esoteric practitioner embodies the characteristics of the Buddha. The correct recitation of a buddha’s mantra identifies the reciter with the speech of the Buddha. Mantras are the language of enlightened beings, and mastering this secret language opens a channel of communication with the Buddha. Finally, to see things as they truly are is to know the mind of the Buddha. In esoteric Buddhism, this abstraction is represented by the iconography of the mandala. Mandalas are the cosmos seen from the perspective of a fully awakened being. By generating the buddhas, bodhisattvas, deities, and alternative realms depicted in the mandala in one’s own mind, the adept unites his or her mental actions with the secret activity of the Buddha.

In essence, the practice of cultivating the three secret activities is a theory of ritual. Whether singing hymns, undertaking austerities, or focusing on calming the mind, the practitioner must follow an established set of protocols in order to achieve the desired spiritual aims. By mimicking the three activities of the Buddha, the esoteric Buddhist acolyte sets forth on a path toward purifying the body, speech, and mind, ultimately leading to the attainment of buddhahood. The methods for achieving such a lofty goal are accessible to the modern practitioner only because the necessary ritual protocols have been tested, refined, and transmitted by past masters.

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The soteriological process of the three secret activities is contingent on the inherent capacity for all beings to become a buddha, not only in the distant future after numerous rebirths but in one’s current body. If the esoteric practitioner correctly emulates the activities of a buddha, then he or she can see the body of the buddha, hear its voice, and comprehend its thoughts. Thus, the three secret activities of the Buddha coexist with the three activities of sentient beings. By unifying one’s three activities with the activities of a buddha, the practitioner will see his or her own body as the Buddha, hear his own voice as the voice of the Buddha, and realize that his own thoughts are the mind of the Buddha. As a style of deity yoga, this practice aims to guide the initiate toward the ultimate realization that the secret activities of the Buddha and the actions of the practitioner are essentially nondual and indistinguishable. In other words, if you look like a buddha, talk like a buddha, and think like a buddha, then you must be a buddha.

The cultivation of the three secret activities is fundamental to both the Mount Hiei (Tendai) and Mount Koya (Shingon) traditions of esoteric Buddhism. Although the notion that the Buddha possesses such actions was commonplace in East Asia well before the translation of esoteric texts, the proposition that it is possible for sentient beings to realize such secrets is definitive of esoteric Buddhism. Therefore, in addition to the historical and liturgical features of the esoteric schools of Japanese Buddhism, the doctrine of the three secret activities distinguishes them from other Mahayana traditions.

Finally, we might say that the secret teachings of the Buddha are internal to our own bodily, verbal, and mental actions and accessible to us thanks to the transmission of practices that have been passed down by elite groups of ritual masters. However, reflecting on this doctrine of mimetic buddhahood, I can’t help but wonder if it was intended to be taken literally—or are the three secrets of the Buddha a metaphor for the path to becoming a buddha? If the secret activities of the Buddha mirror the actions of sentient beings, and it is possible for sentient beings to realize these secrets, then isn’t the cultivation of these perfected activities just a metaphor for our own liberation from negative karmic output?

Since I was first introduced to Japanese esoteric Buddhism many years ago, I have often pondered this question and have come to think that yes, this doctrine is a metaphor. But that does not diminish its salvific value. Navigating the fuzzy line between metaphor and reality is an essential component of religious thought and practice. Crossing the sea of samsara, for example, is a metaphor for passing from our world, with all its familiar experiences of suffering, into an uncertain existence (or nonexistence, as the case may be) in which all such suffering has been extinguished. Metaphors allow us to express the ineffable and explain the incomprehensible. Esoteric Buddhism seizes on such metaphors not merely as abstract concepts but as methods for crossing from the known to the unknown and, ultimately, for becoming a buddha.