Rishu-kyo (Principle of Wisdom Sutra) (理趣経)

"Rishu-kyo" is the Buddhist scriptures of Esoteric Buddhism, which is Part Six of 'Kongocho-kyo' (Vajrasekhara Sutra). It is recited mainly in each school of the Shingon sect. It is called adhyardhaśatikā prajñāpāramitā ("Hyakugoju ju Hannya" [The Wisdom Sutras of Praise in 150 Verses]) in Sanskrit.
"Rishu-kyo" is the abbreviation for 'Taira kinko fuko shinji sanmaya kei' (the Sutra preaching on a state of Buddhahood in which it is realized that great pleasure is permanent like diamond, not vanity but real) or 'Hannya haramita rishubon.'

History

Fuku was generally said to have translated it from 763 to 771.

However, because Xuanzang's translation of the Hannya Rishubun (gate for understanding hannyaharamitta) section of part 10 of the "Daihannyaharamitta-kyo" is regarded as being a different translation of "Rishu-kyo," it is believed that the group who compiled "Shinjitsusho-kyo" (Part one of Kongocho-kyo) developed a text in the line of the 'Hannya-kyo Sutra' into "Rishu-kyo" as Esoteric Buddhist scriptures.

Summary

Since this sutra is known as "Hannya haramita rishubon" (its original title is "Hyakugoju ju Hannya"), it is seen as Buddhist scriptures in Hannya section; however, some think that it is placed in the groups of Esoteric Buddhist scriptures in Hodo section in terms of content.

It is the custom in the Shingon sect to chant "Rishu-kyo" in daily devotional exercises, which stresses the virtue of chanting sutras, among the primal scriptures "Dainichi-kyo Sutra" and texts of 'Kongocho-kyo' which is composed of 18 parts.

Although Buddhist scriptures are usually read in the Wu reading, in the Shingon sect it is chanted in the Han reading of Chinese characters based on the Chinese pronunciation at the time when "Rishu-kyo" was introduced into Japan.
For example, the title of Buddhist scriptures '大楽金剛不空真実三摩耶経' is pronounced 'Taira kinko fuko shinji sanmaya kei.'

Composition
"Rishu-kyo" is composed of 17 chapters except the Introduction in the beginning and Rutsu (circulation of Buddhism teachings) at the end.

Homon (the teachings of Buddhism) of Great Pleasure Chapter of Kongosatta (Vajrasattva)
Homon of Shogo (to disabuse and become enlightened) Chapter of Dainichi Nyorai (Mahavairocana)
Homon of Surrender Chapter of Shakamuni Nyorai (The Buddha Shakamuni)
Homon of Contemplation Chapter of Kanjizai Bosatsu (bodhisattva)
Homon of Wealth Chapter of Kokuzo Bosatsu (Akasagarbha Bodhisattva)
Homon of Working Chapter of Kongoken Bosatsu (Vajrasandhi Bodhisattva)
Homon of Jirin (words having no form) Chapter of Monjushiri Bosatsu (Manjushiri Bodhisattva)
Homon of Jutairin (entering a state of full and peaceful large ring) Chapter of Saihasshintenborin Bosatsu (Sahacittotpadadharmacakrapravarti Bodhisattva)
Homon of Kuyo (to hold a memorial service) Chapter of Kokuko Bosatsu
Homon of Anger Chapter of Saiissaima Bosatsu
Homon of Fushu (putting together wisdom) Chapter of Fugen Bosatsu (Samantabhadra Bodhisattva)
Homon of Humanity and Incantation Chapter of Gods in external Vajradhatu group
Homon of Goddesses Chapter of Seven Goddesses
Homon of Three Brothers Chapter of Three High Gods
Homon of Four Sisters Chapter of Four Heavenly Maidens
Homon of Each Division Chapter of Great Mandala in Shiharamitsu (four paramita)
Homon of Mystery Chapter of Five Kinds of Samadhi (higher level of meditation)
Each chapter includes mudra (symbolic hand gesture used in Buddhism) and mantra plainly showing the contents, and Shingon Buddhist monks learn these mudra and mantra as required.

Seventeen Pure Phrases

Shingon Esoteric Buddhism is based on the idea 'pure human nature'. Although this idea is contrasted, or identified with Hongaku philosophy in the Tendai sect, it tells that people are pure beings by nature. "Rishu-kyo" is characterized by teachings based on the idea of a pure human nature, which assumes that people's activities are naturally pure.

In particular, in Homon of Great Pleasure at the beginning, 17 poems called 'Seventeen Pure Phrases' are taught.

The exquisite rapture in sexual intercourse is a clean mental state of Bosatsu. The exquisite rapture in sexual intercourse is a clean mental state of Bosatsu. Desire moving quickly and violently like arrow is a clean mental state of Bosatsu. Desire moving quickly and violently like arrow is a clean mental state of Bosatsu. The physical contact between man and woman is a clean mental state of Bosatsu. The physical contact between man and woman is a clean mental state of Bosatsu. Loving the other sex and embracing each other tightly is a clean mental state of Bosatsu. Loving the other sex and embracing each other tightly is a clean mental state of Bosatsu. Man and woman embracing each other satisfied, being free from everything and the master of everything, and being exalted is a clean mental state of Bosatsu. Man and woman embracing each other satisfied, being free from everything and the master of everything, and being exalted is a clean mental state of Bosatsu. Looking at the other sex with desire is a clean mental state of Bosatsu. Looking at the other sex with desire is a clean mental state of Bosatsu. Man and woman making love and feeling great pleasure is a clean mental state of Bosatsu. Man and woman making love and feeling great pleasure is a clean mental state of Bosatsu. Love between man and woman is a clean mental state of Bosatsu. Love between man and woman is a clean mental state of Bosatsu. Being proud of himself/herself is a clean mental state of Bosatsu. Being proud of himself/herself is a clean mental state of Bosatsu. Taking pleasure in decoration is a clean mental state of Bosatsu. Taking pleasure in decoration is a clean mental state of Bosatsu. Being pleased that things go as he/she wishes is a clean mental state of Bosatsu. Being pleased that things go as he/she wishes is a clean mental state of Bosatsu. Being satisfied and the mind lit up with joy is a clean mental state of Bosatsu. Being satisfied and the mind lit up with joy is a clean mental state of Bosatsu. Physical comfort is a clean mental state of Bosatsu. Physical comfort is a clean mental state of Bosatsu. Color to see with our own eyes is a clean mental state of Bosatsu. Color to see with our own eyes is a clean mental state of Bosatsu. Sound to hear with our own ears is a clean mental state of Bosatsu. Sound to hear with our own ears is a clean mental state of Bosatsu. Scent in this world is a clean mental state of Bosatsu. Scent in this world is a clean mental state of Bosatsu. Taste to savor with our own mouth is a clean mental state of Bosatsu. Taste to savor with our own mouth is a clean mental state of Bosatsu. Thus Seventeen Pure Phrases are daringly positive about sexual intercourse and human act.

Exoteric Buddhism is more likely to be negative about sexual intercourse.
On the other hand, because "Rishu-kyo" is not entirely negative about desires as shown above, it is often looked on from a biased viewpoint such as 'sex-affirmative scriptures.'
However, these phrases plainly express the pure human nature of Shingon Esoteric Buddhism, and the essence of the scriptures is to explain that human actions, ideas and activities are themselves naturally pure.

Many people wrongly believe that Seventeen Pure Phrases are merely desire-affirmative, or that being desire-affirmative (or sexual intercourse) leads to Sokushin-Jobutsu (attaining Buddhahood while still alive).

Therefore, there is a strict regulation that "Rishu-kyo" should not be taught before Buddhists conduct shidokegyo (four trainings) for preparatory practices. The final 17th act in "Rishu-kyo" is called 'Poem of One Hundred Characters,' constituting the central part in the scriptures. According to the teaching, it is important for Shingon Buddhist monks to risk their lives to live for the benefit of the people with great desires; and it is the duty of Shingon Buddhist monks to have a clean feeling untouched by mire, and to wish for the benefit of the people with great desires.

These ideas are found in 'Juhobengakusyobon' of "Dainichi-kyo Sutra," one of two principle texts of Daiho (great traditions of Esoteric practices).

Development
Regarding what is taught in this Seventeen Pure Phrases many interpretations and study have been made from ancient times, and incidents occurred.

The incident regarding borrowing of Buddhist scriptures by Saicho is especially well-known. Saicho, who was the Founder of Nihon Tendai sect, became the disciple of Kukai, who was still nameless and young at that time, and Saicho received kanjo (a consecration ceremony by pouring water onto the top of monk's head). Because Saicho, who aimed to establish Tendai doctrine, was very busy, he frequently made his disciples borrow Buddhist scriptures from Kukai. However, when Saicho tried to borrow "Rishushakukyo," an explanation book of "Rishu-kyo," Kukai finally declined to lend it. This was a admonition to Saicho, who tried to understand Esoteric Buddhism superficially by making a handwritten copy of Sutra, not mastering the method in esoteric Buddhism; Kukai declined to lend the scriptures insisting that Esoteric Buddhism laid importance not only on scriptures but on ascetic practices and Face to Face Transmission. Although the reason why Kukai declined remains unknown, it is generally believed that Kukai feared the misinterpretation that Seventeen Pure Phrases in "Rishu-kyo" taught sexual intercourse led to jobutsu (to become a Buddha).

Later on Kukai reorganized To-ji Temple as the complete Esoteric Buddhism temple, and prohibited Buddhist monks other than Shingon Esoteric Buddhists from entering; and he made a strict regulation that only disciples selected by him could study only Buddhist scriptures and originals selected by him; however, "Rishu-kyo" was not included even in these.

In the Kamakura period the Tachikawa-ryu (Esoteric Buddhism), a school of Shingon Esoteric Buddhism based on "Rishu-kyo," was founded, and it was later oppressed as an evil heresy.
(However, it is controversial whether the Tachikawa-ryu should really be seen as heresy, because there remained no books on the side of Tachikawa-ryu although there remained many books on the side of oppressors of Tachikawa-ryu.)