Shingon Buddhism
The Esoteric Tradition

The second One Vehicle School of Heian Buddhism is Shingon, which is based on the Chinese Chenyan (sic) School. The name of the school means “True Word” and refers to the mantras used in its Tantric practices. Shingon, then, is a Japanese form of Tantric or esoteric Buddhism. Indeed, because Tendai also uses Tantric elements, Heian Buddhism is sometimes referred to as the “esotericization” (mikkyoka) of Japanese religion. ...
Exoteric vs. Esoteric
The doctrine revealed by the Nirmanakaya Buddha [Shakyamuni Buddha] is called Exoteric; it is apparent, simplified, and adapted to the needs of the time and to the capacity of the listeners. The doctrine expounded by the Dharmakaya Buddha [Mahavairocana] is called Esoteric; it is secret and profound and contains the final truth. [Kukai: Major Works, 63]

What’s the significance of this distinction between
“Exoteric” and “Esoteric” Buddhism?

The founder of Shingon was Kukai (774-835). Kukai entered a state university at the age of eighteen and studied the Confucian classics. At the university, he met a Buddhist monk who showed him a scripture with esoteric passages. This inspired Kukai to leave the university. He took up the life of a wandering ascetic, and during his travels read Buddhist texts. One text was the Mahavairocana Sutra from the mature Tantric tradition. Kukai was attracted to its promise of sudden Awakening to the inner essence of Buddhahood, but was not able to understand the esoteric use of mudras, mantras, and mandalas that the text advocated for this attainment. So, he decided to travel to China to find a teacher who could teach him this esoteric path. In 803, he became ordained as a Buddhist monk and left for China the next year.
In China, Kukai received his training from the great Tantric master Huiguo (746-805). Huiguo had received transmission from two Tantric lineages: one based on the Mahavairocana Sutra, and the other based on the Vajrasekhara Sutra. Under Huiguo, Kukai received initiation into the meditative techniques associated with both Tantric lineages, and then received ordination as a Tantric master. In 806, Kukai returned to Japan with mandalas, scriptures, and Tantric ritual materials. In 809, the emperor ordered Kukai to serve at Takasan-ji, the temple that was the center of the Heian Buddhist world. There, Kukai systematized Tantric doctrines, organized Tantric materials and sutras, and vigorously propagated Tantric Buddhism. In 816, the emperor gave Kukai permission to build a monastery on Mt. Koya, some distance from the capital. Until his death in 835, Kukai was also in charge of To-ji, a temple in the capital that was to be a center for Tantric art and practice. [Buddhism: Introducing the Buddhist Experience, 318]

The teachings of Shingon are intended to guide people to [the] tenth stage of virtuous Buddha-consciousness. They do so by stressing that the highest Buddha is the Dharmakaya, the essential enlightenment nature of Buddhahood. This Dharma-body is a luminous reality of wisdom and compassion that penetrates and embraces all existence such that the Dharmakaya is actually one’s own innate Buddha-nature. Kukai identified this ultimate suchness of the universe with Vairocana Buddha, symbolized by the sun, which radiates its light to all beings in the universe. For Shingon, Vairocana, as the Dharma-body of the universe, preaches and acts continuously throughout the cosmos. ...

The Rise of Shingon Buddhism
Mahavairocana (Dainichi) means “Great Sun.” It is understandable that Kukai, when he discovered the Mahavairocana Sutra, should have felt a special affinity with the Great Sun Buddha. The Great Sun Goddess (Amaterasu) is the central figure in the Shinto pantheon, and the parallel between the two is too obvious to need stressing. Later, with the development of Ryobu Shinto, Amaterasu came widely to be recognized as an avatar [i.e. a manifestation] of Dainichi Nyorai (Tathagata), and Kukai could hardly fail to reach a comparable conclusion. [Kukai, 81]
Shingon also teachs that the secret and constant teaching of the Dharmakaya can actually be communicated to a person through the mysterious words, symbols, and ritual movements of Tantric Buddhism. The mantras that one recites bring into awareness Vairocana’s speech, the mudras that one forms with his or her hands give one a felt sense of Vairocana’s body, and the mandalas on which one concentrates bring forth Vairocana’s state of mind. Thereby, one unlocks the Three Mysteries (sanmitsu) of Vairocana: his speech, body, and mind in the universe. ... Shingon believes that by realizing these mysteries in one’s own experience, the long journey to Buddhahood, which in the other traditions may take eons to complete, can be attained in just one lifetime and in one’s very mind and body. [Buddhism: Introducing the Buddhist Experience, 319-20]
In a word, the essence of Kukai’s Esoteric Buddhist meditation is simply “imitating.” This is technically called the practice of “entering self into Self so that the Self enters into the self (nyuga ga’nyu).” The self is the individual existence and the Self, Mahavairocana. To practice the samadhi of Mahavairocana is to imitate it through one’s total being — physical, mental, moral, intellectual, and emotional — like an actor acting alone on stage. The stage is the sacred ground (mandaladojo). This can be anywhere as long as it is ritualistically consecrated, but it is usually the main hall of a temple where a principal Buddha or bodhisattva or any other manifestation of Mahavairocana is enshrined. Here the eternal and cosmic drama of the samadhi of self-enjoyment (jijyu o sammai) of Mahavairocana is performed through rigidly prescribed activities of body, speech, and mind, every step exactly as prescribed: how to move one’s fingers (mudra); what to think or visualize or feel; and which mantra to recite at what moment and how many times.
On performing the rituals of purification and consecration of the ground and of the ten directions, the circle where the student meditates is transformed into the center of the universe. Then begins the invocation of the presence of Mahavairocana, or of any of his manifestations, as the object of meditation confronting the subject, followed by a conscious effort to imitate the object through symbolic activities of body, speech, and mind. The climax is reached when the subject, while performing the acts of imitating, loses the awareness that he is imitating — the subject is transformed into the object, and the separation between the subject and the object disappears. In the end, as the actor withdraws from the stage, the subject returns to the imitating self, and the object, to where it came from, by means of ritual acts. The entire process is regulated by rules, that is, the process of time is punctuated by prescribed activities so that the student will not lose himself in timelessness; step by step he returns from unconscious imitating to his conscious self by counting beats, striking a hand bell, and so forth. [Kukai, 98-9]

Mandala of the Two Worlds
“Since the Esoteric Buddhist teachings are so profound as to defy expression in writing, they are revealed through the medium of painting.” [Kukai, 80]
Broadly speaking, the Diamond World mandala represents reality in the buddha realm, the world of the unconditioned, the real, the universal, and the absolute. The Womb World mandala represents reality as it is revealed in the world of the conditioned, the individual, the particular, and the relative. Each mandala is fully meaningful, however, only when paired with the other. [Japanese Mandalas: Representations of Sacred Geography, 37]

In Shingon, two mandalas have a special place in bringing the virtuous and enlightened qualities of the Three Mysteries into one’s experience. First is the Womb or Matrix (taizo) Mandala, based on the Mahavairocana Sutra. This mandala represents an enlightened view of the universe from the viewpoint of compassion, and implies that the energy of compassion enfolds, protects, and nurtures one’s Buddha-nature like a womb holding a child. The many deities of this mandala represent the activities of compassion; in Tantric experience, they foster this same compassion in the practitioner. This first mandala, symbolized by the lotus, represents the compassionate gentleness of the universe evolving from unity to diversity. ...
In [the Womb World] mandala, all kinds of Buddhas and deities are lined up together. If we ask if only the very magnificent Buddhas are lined together, the answer is no. Only the cosmic Buddha Dainichi Nyorai [a.k.a. Mahavairocana] in the center is one hundred percent perfect. Many of the others surrounding it are deities from Indian folk religion. On the very outer edges, a lot of snakes and demons have been included. Now each one of them is an offshoot of Dainichi Nyorai. Each has some kind of special characteristic, and each can become a Buddha by means of that special characteristic. What we find here is a logic by which even something that is ninety-nine percent bad has a hundred percent value by virtue of the one percent of the special characteristic it has. … Therefore there is no such thing as leaving behind something that is ninety-nine percent bad. Because they have a special characteristic in the amount of one percent, they are seen as an offshoot of the one hundred percent that is Dainichi Nyorai. Such a world is woven into the mandala. It is a way of thinking in which everything is embraced and every single special characteristic is nourished. [Japanese Mandalas: Representations of Sacred Geography, 58]
The second mandala is the Diamond (kongokai) Mandala, based on the Vajrasekhara Sutra. In this mandala, the universe is united in the light of wisdom that merges all beings into one. This wisdom concentrates all the universe into the single light of Vairocana Buddha, who is the luminous source of all the mandala’s deities. Penetrating this mandala in Tantric experience is said to infuse the practitioner with the light of wisdom, and transforms his or her life into Awakening. This mandala balances the gentleness of compassion in the Womb Mandala by representing the diamond hardness of wisdom that cuts through illusion and brings diversity into unity. ...
At the center of the Diamond-world mandala ... is a square called the “Attainment Body” assembly. ...
In the center is Vairocana, who manifests four additional Buddhas, each located at the center of each of the squares surrounding Vairocana. ... The four smaller figures around each Buddha are Bodhisattvas, who serve as more specific aspects of that particular Buddha’s wisdom. The use of multiple deities to represent a movement from abstract qualities to their specific applications is a common symbolic device in Mahayana Buddhism. []
By using these two mandalas with the esoteric practice of mantras and mudras, the Shingon practitioner seeks to unite his or her human activities (speech, body, and mind) with the Three Mysteries of the universe — the speech, body, and mind of Vairocana Buddha in all things. The experience of this union with the Three Mysteries brings about a “mutual empowerment” in that both the practitioner and the Buddha are affected. While the practitioner attains Awakening and Buddhahood, Vairocana Buddha actualizes Buddha-nature more fully in the phenomenal world, since every act of the enlightened person is an action of the Three Mysteries. In this transformation process, the practitioner is guided by a Tantric master who alone has the ability to transmit these potent teachings and practices. [Buddhism: Introducing the Buddhist Experience, 320-1]

Shingon Initiation
The mandala of the Two Worlds is found in Shingon temples and monasteries and is also found in Tendai settings that emphasize Esoteric teachings. For public ceremonies, the two mandalas are hung facing one another on the western (Diamond World) and eastern (Womb World) walls of the main sanctuary, with the central altar between them. Smaller square altar platforms representing horizontal mandalas are set up in front of each two-dimensional mandala. These platforms are covered with ritual implements such as vajras and vajra bells, with offerings such as flowers and candles, and with bowls and dishes for water and incense. The mandalas are also used in various initiation rites known as kanjo (S. abhiseka). For the critical first initiation, both monks and laypeople are led blindfolded into a sanctuary in which one of the two mandalas has been laid out on a low altar. The initiates are given flowers or sprigs (usually of anise) to throw. The sacred figure on whom a sprig lands is designated the personal deity with whom that particular devotee will now begin the practice of realizing the unity of body, speech and mind. A tradition going back to the time of Kukai holds that when Kukai underwent his initiation guided by Huiguo, his flower landed on none other than the central, primordial buddha, Mahavairocana/Dainichi. [Japanese Mandalas: Representations of Sacred Geography, 37]