金光明經文句記 6.168

6.168

二「希有」下一行，約喻。即喻上報身智行也。大海，喻智也。須彌，喻行也。其智冥理，窮實相底，故方之大海。《釋論》謂「智度大海，佛窮其底。」因中萬行積功累德，喻彼須彌，如《華嚴》、《涅槃》皆云「析骨書經，如彼妙高。」

Second, the single line from "Rare" is in terms of analogy. That is, it analogizes the wisdom and practice of the Reward Body above. The great ocean analogizes wisdom; Mount Sumeru analogizes practice. His wisdom unites with principle and plumbs the bottom of the true mark; hence it is compared to the great ocean. The Shilun states: "The great ocean of the perfection of wisdom—the Buddha plumbs its bottom." The myriad practices in the causal stage accumulating merit and gathering virtue are analogized to Mount Sumeru, as both the Avataṃsaka and Nirvāṇa sūtras say: "Splitting bones to write sūtras, [piled] like that Wondrous High [Mountain]."