The Buddhist bokjang (腹臟, interring of objects within inner recesses of Buddhist images) was more systemized based on Josang gyeong (造像經, Sūtra on the Production of Buddhist Images ) during the Joseon period, after it settled down to a formalized format in the Goryeo period. The Josang gyeong , which articulates complex thoughts and content based on multiple scriptural sources, contributed to forming a standard for the Korean Buddhist bokjang by combining the immaterial Buddhist ritual with materialistic interring of objects. The bokjang , therefore, is the only example that not only shows ritualistic acts as a byproduct of religious belief but also preserves the outcome. Conserving original religious thoughts and ritualistic features made this possible.
This dissertation aims to illuminate the comprehensive characteristics of the bokjang in Korean Buddhism. In order to do this, I analyze the origin and the meaning of the Korean bokjang , its chronological development, Buddhist painting reflecting the immaterial bokjang ritual, and finally, religious thoughts that were formalized to the idea of five directions. Because my research is based on the Josang gyeong , it narrows down to the objects relating to the throat-bell container (喉鈴筒, an eight-petal bottle (八 葉筒) in the Goryeo).
This study also defines spatial and ritual extent through the concept of bokjang in the Goryeo period. The Goryeo period’s bokjang installed an eight-petal container, five treasure bottles (五寶甁), five-wheel seed syllables (五輪種子), and true-mind seed syllables, symbolizing the five Buddhas (眞心種子) within the inner recesses of Buddhist images (腹藏孔). This established a new and unique method of Buddhist ritual, completely separate from the early phase of bokjang practice in Korea, which concentrated on relic worship before the Goryeo period. In the Joseon period, based on the Josang gyeong , the center of the bokjang moved to the throat-bell container, which resulted in changes in the format of the five treasure bottles and also newly set up the following items, all of which created the practices’ distinctiveness: Spells of the Four Directions (四方呪), five-directional mirrors (五方鏡), banners (幡), canopies (傘盖), and vajras (金剛杵) in textile. Even though the list of the items changed in the Goryeo and Joseon periods, the composition of five treasure bottles, five kinds of grains (五穀), five medicines (五藥), five yellows (五黃), five aromas (五香) and five treasures (五寶), and the format of the five-wheel seed syllables and the true-mind seed syllables are identical to the Yongcheonsa (龍泉寺) edition of the Josang gyeong in 1575. It is highly possible that the bokjang in the Goryeo period would have been based on a similar sutra or text to Josang gyeong , even though no scriptural evidence is left. In contrast, China and Japan already have similar practices, called zhuangcang (裝藏) and nōnyūmono (納入
物), respectively. The practice’s scope covered even a throne in terms of space, and its subject extended to various images including Buddhist sculptures. For example, five viscera and six entrails and relics in the Tang period and reliquaries in shape of gorintō (five-ringed tower, 五輪塔) during the Kamakura period in Japan became essential items
in the practice. In particular, in Japan during the contemporaneous period to Goryeo, the types and compositions of the items for interring objects became simplified, which is different from the Korean bokjang practice.
The Korean bokjang was expanded to Buddhist painting in the Joseon period. The composition of bokjang in the painting was identical to that of Buddhist sculpture, but the method of installing the objects and the location varied. In particular, the items represented as siddha letters in “Je bulbosal bokjangdan uisik (諸佛菩薩腹臟壇儀式)” or the “Altar Ritual of Interring Objects within [Images of] All the Buddhas and Bodhisattvas” section in Josang gyeong and mantras that were recited in the course of a ritual as prescribed in the “Myogilsang daegyowang gyeong (妙吉祥大敎王經)” or the “Great King of Tantras of the Triumphant Meditation” section in the Josang gyeong were directly written on a Buddhist painting. The siddha letters are recorded on the faces and bodies of Buddhist deities, so that they become enlivened by dotting their eyes.

The letters on the painting clearly represent a major characteristic of bokjang practice in Korea because it verifies not only material items as seen in Buddhist sculptures but also an immaterial ritual that connects an actual ritual and the related objects. Based on the concept of f ive Buddhas and f ive wisdoms (五智) shown in Mahāvairocana Sūtra (大日經) and Vajra ekara Sūtra (金剛頂經) of the Esoteric Buddhism of the middle phase, Josang gyeong explains five treasure bottles, five kinds of grains, five medicines, five yellows, five aromas, and five treasures in relationship with the five directions and five Buddhas. The five wisdoms of the five Buddhas are composed of the five-directional mirrors and five-wheel seed syllables. In Korean bokjang , “five directions” does not simply mean bearings but the place where the five Buddhas reside, and corresponding items symbolize the five Buddhas and five wisdoms. Doctrines of garbha-dhatu and vajra-dhatu of the Esoteric Buddhism of the middle phase became united in the late phase. Related sutras such as Sanzhong xidi sanbu yigui (三種悉地三部儀軌) and Miaojixiang pingdeng mimi zuishang guanmen dajiaowang jing (妙吉祥平等袐密最上觀門大敎王經) were added to Josang gyeong as “Sam silji danseok (三悉地壇釋)” or the “Commentary on the Mandala of the Three Siddhis” section and “Myogilsang daegyowang gyeong (妙吉祥大敎王經)” or the “Great King of Tantras of the Triumphant Meditation” section, respectively. By doing this, the five-wheel seed syllables and
secret-siddhi (秘密悉地) successfully represent the unification of the garbha-dhatu and vajra-dhatu thoughts. The bokjang ritual performed by a dharma master of spell chanting (誦呪法師), preceptor (阿闍梨, Skt. ācārya), and ritual masters of the five directions (五方法師) were influenced by Foshuo tuoluoni ji jing (佛說陀羅尼集) and the Miaojixiang pingdeng mimi zuishang guanmen dajiaowang jing (妙吉祥平等袐密最上觀門大敎王經). The sections in Josang gyeong reflect such influence because they are reorganized as follows: “Myogilsang daegyowang gyeong,” “Geumgang asari gwansang uigwe (金剛阿闍梨觀想儀軌),” and “Bokjangdan junghoeui (腹臟壇衆會儀).”
Even though the philosophy and ritual of Josang gyeong was founded upon the Esoteric Buddhism of both the middle and late phases, it is, in fact, pertinent to the consecration ritual with water of the five vases (五甁灌頂儀式). “Myogilsang daegyowang gyeong,” for example, focuses on a ritual process based on the five treasure bottles. Because of this, it is difficult to find explicit characteristics of the eight-petal container and the throat-bell container that provide vitality to a statue so that it can be the object of religion and faith. However, by combining eight petals representing a human’s heart with five treasure bottles in which five Buddhas are installed, the eight-petal container becomes an object that embraces the concept of the central eight-petal court (中台八葉院) from garbha-dhatu of the Mahāvairocana Sūtra . In addition, manifesting the five Buddhas’ wisdom externally by winding five-colored threads around the five treasure
bottles and through a “throat-hole (喉穴)” drilled in the lid of the throat-bell container, and this being connected to the five-directional mirrors, is strikingly similar to the way in which Vairocana Buddha’s wisdom is manifested vocally by Vajragha ā (金剛鈴菩薩), the last bodhisattva among 37 deities in the Vajra ekara Sūtra .
In sum, the Korean bokjang practice is deeply associated with E soteric Buddhism developed after Mahāvairocana Sūtra and Vajra ekara Sūtra , as seen from the composition of the interring objects but also writing the siddha letters on the bodies of the deities as a way of dotting the eyes. Furthermore, by incorporating other thoughts, such as Daoism and yin and yang and five elements, which cannot be found in the practice of interring objects in China and Japan, the bokjang contributes to establishing Korea’s own Buddhist culture.