The Myth of the South Indian Iron Stupa (Nanten tettō) in Japanese Esoteric Buddhism

Abstract

According to a legend, recorded in China in the second half of the eighth century by Amoghavajra (Bukong 不空, 705–774), the most influential patriarch of Esoteric Buddhism (mikkyō 密教) during the Tang, the teachings of the Vajraśekhara Tantra (Ch. Jin’gangding jing, Jp. Kongōchōgyō 金剛頂経) were transmitted to an unnamed sage in south India (Nanten 南天, an abbreviation of Nan-Tenjiku 南天竺) from inside a mysterious iron stūpa (tettō 鉄塔). A few decades later, Kūkai 空海 (774–835), the founder of the Shingon school 真言宗 in Japan, identified that sage as Nāgārjuna, who came to be considered the third patriarch of Shingon Buddhism. Since then, that of the South Indian Iron Stupa (nanten tettō 南天鉄塔) has been an important theme in Japanese religious history; in particular, it became a symbol of the transmission of esoteric knowledge in intiation/consecration rituals (kanjō 灌頂) and was later transferred and adapted to newly created Buddhist rituals for Japanese deities (kami 神) known as jingi kanjō 神祇灌頂 or shintō kanjō 神道灌頂. This article explores some of the aspects of the myth and its doctrinal implications, especially regarding the epistemology and soteriology of Esoteric Buddhism. After a brief discussion of the Iron Stupa myth from East Asian canonical sources and Kūkai’s ideas about the tranmission of Esoteric teachings, I move on to examples of esoteric exegeses of this myth, both from the Shingon and Tendai denominations—as typical in such interpretive endeavors, the words of the myth, their meanings and their (supposed) external referents (objects and states of the world) are disassembled and recombined according to the principles of medieval Buddhist semiotics. Next, I trace further developments of the Iron Stupa myth as a central image in medieval rituals about Japanese kami. In the final considerations section I offer some elements to place this myth within the larger context of the system of meaning of Esoteric Buddhism.