華嚴一乘教義分齊章 1.53

1.53

3. According to Vinaya Master Guangtong [Huiguang], he established three kinds of teachings: gradual, sudden, and perfect. Master Guang's intended explanation was that for those whose faculties are not yet mature, he first taught impermanence and later taught permanence, first taught emptiness and later taught the profound and wondrous meaning of non-emptiness. Because it was taught in such a progression, it is called the gradual teaching. For those whose faculties are mature, within a single doctrinal approach he fully expounded all buddha-dharmas, teaching permanence and impermanence, emptiness and non-emptiness simultaneously without any progression; hence it is called the sudden teaching. For those of superior attainment who have reached the stages of the Buddha's realm, he taught the Tathāgata's unobstructed liberation, the ultimate fruition-ocean, the supremely perfect, secret, and sovereign doctrinal approach—which is this sūtra. Later disciples under Guangtong, such as Master Zuntong and other worthies, all inherited this tenet and largely concurred with this explanation.