Filling In What the Founder Left Unfinished

Saicho died in 822 having established the principle that esoteric and exoteric teaching belonged together but without having built out an esoteric curriculum to match Shingon's in depth. That work fell to his successors. Ennin traveled to Tang China from 838 to 847 and Enchin followed a similar path a few years later, each returning with additional esoteric texts, ritual instructions and lineage transmissions that were folded into what came to be called Taimitsu, Tendai's own esoteric tradition, distinguished by name from Tomitsu, the Shingon esotericism Kukai had brought back a generation earlier. The two successors' separately built esoteric lineages did not simply merge into one settled Tendai practice. Differences between what Ennin and Enchin had each transmitted contributed to a rift that eventually split the school administratively into the Sanmon faction centered on Enryakuji and the Jimon faction centered on Onjoji, later called Mii-dera, a division that persisted for centuries and turned an argument about esoteric lineage into a fight over which monastery controlled the head temple's own succession. The rivalry was not merely administrative: armed monks based at Enryakuji on Mount Hiei attacked and burned Onjoji's buildings on repeated occasions over the following centuries, a level of violence that turned a disagreement traceable back to two returning pilgrims' separately acquired esoteric transmissions into one of premodern Japan's most persistent instances of intra-Buddhist armed conflict.