By Zongmi's own lifetime, Chan Buddhism had begun to define itself against exactly the kind of systematic doctrinal study Huayan represented, favoring instead a direct pointing at Buddha nature that treated scripture and philosophy as, at best, a finger pointing at the moon and at worst an obstacle. Zongmi held credentials on both sides of that divide, a Chan lineage holder in the Heze branch descending from Shenhui, and the fifth patriarch of Huayan, and he used the position not to pick a side but to argue the split itself was a mistake.
His Inquiry into the Origin of Humanity ranked the major Chinese teachings, Confucian, Daoist and several tiers of Buddhist doctrine, by how completely each accounted for the origin and destiny of human beings, a scheme obviously indebted to his teacher's teacher Fazang's own ranking of the Buddhist schools, with a fully worked out Huayan-Chan synthesis at the summit. His practical point was more durable than the ranking itself: Chan's sudden insight into one's own already-present Buddha nature, he argued, still needs the patient doctrinal study Huayan philosophy provides to be understood correctly and not mistaken for licence, while doctrinal study without the direct experience Chan practice cultivates remains abstract and unrealized. Sudden awakening, gradual cultivation, in his famous formula, are two moments of one process rather than two rival schools. Zongmi died in the same decade, 841, that opened into the great Buddhist persecution of 845, and the Huayan school he had tried to keep alive as an independent institutional force did not really survive it; but the harmonizing move he made, treating meditation and doctrine as partners rather than rivals, shaped how later Chan across East Asia justified its own relationship to scripture and study.