Four Rivers from Four Mouths
The chapter turns from lists to landscape. Lake Anavatapta has four openings shaped as an elephant, a lion, an ox and a horse; from each a great river pours, over sand of silver, diamond, gold and beryl, circling the lake seven times before it runs to the sea.
Every Samādhi, Seen Through
Before the simile, the claim it is meant to illustrate: not only that all samādhis are known, but that every phase of each of them is visible — entering, rising, abiding, appearance, aftermath, and how it ends.
「佛子！菩薩摩訶薩住此三昧，能了知無數、無量、無邊、無等、不可數、不可稱、不可思、不可量、不可說、不可說不可說一切三昧。彼一一三昧，所有境界無量廣大，於境界中若入、若起、若住，所有相狀，所有示現，所有行處，所有等流，所有自性，所有除滅，所有出離，如是一切靡不明見。
"Child of the Buddha! A bodhisattva mahāsattva abiding in this samādhi can comprehend numberless, measureless, boundless samādhis, samādhis without equal, samādhis that cannot be counted, cannot be reckoned, cannot be conceived, cannot be measured, cannot be spoken, and samādhis ineffably ineffable. In each single one of those samādhis the domain is measureless and vast; and within that domain, the entering, the rising and the abiding; every aspect and appearance; every display; every place of movement; every outflow that follows from it; its own nature; its removal; and its issuing forth — all of this they see clearly, and none of it is unseen.
所有等流 — every outflow that follows from it. 等流 is niṣyanda, what proceeds from something as its natural continuation. Among aspects and displays, this term asks what a samādhi leaves behind in the person afterwards, which is the question Part 504 answered with waking from a dream.
The Lake, and Its Four Mouths
The geography is exact — which animal's mouth, which river, which sand, which colour — and then the rivers circle their source seven times before they leave.
佛子！譬如無熱惱大龍王宮流出四河，無濁無雜，無有垢穢，光色清淨猶如虛空。其池四面各有一口，一一口中流出一河，於象口中出恒伽河，師子口中出私陀河，於牛口中出信度河，於馬口中出縛芻河。其四大河流出之時，恒伽河口流出銀沙，私陀河口流出金剛沙，信度河口流出金沙，縛芻河口流出瑠璃沙；恒伽河口作白銀色，私陀河口作金剛色，信度河口作黃金色，縛芻河口作瑠璃色，一一河口廣一由旬。
Child of the Buddha! It is like the palace of the great nāga king Anavatapta, the Heatless, from which four rivers pour out — unclouded and unmixed, without any impurity, their light and colour pure as open space. That lake has an opening on each of its four sides, and from each opening a river flows out: from the elephant's mouth comes the Gaṅgā; from the lion's mouth comes the Sītā; from the ox's mouth comes the Sindhu; and from the horse's mouth comes the Vakṣu. As those four great rivers pour out, from the mouth of the Gaṅgā there flows silver sand; from the mouth of the Sītā, diamond sand; from the mouth of the Sindhu, golden sand; and from the mouth of the Vakṣu, beryl sand. The mouth of the Gaṅgā is the colour of white silver; the mouth of the Sītā the colour of diamond; the mouth of the Sindhu the colour of yellow gold; and the mouth of the Vakṣu the colour of beryl — and each river-mouth is a yojana wide.
其四大河既流出已，各共圍遶大池七匝，隨其方面四向分流，澒涌奔馳入於大海。其河旋遶，一一之間有天寶所成優鉢羅華、波頭摩華、拘物頭華、芬陀利華，奇香發越，妙色清淨；種種華葉，種種臺蘂，悉是眾寶，自然映徹，咸放光明，互相照現。其無熱池周圍廣大五十由旬，眾寶妙沙遍布其底，種種摩尼以為嚴飾，無量妙寶莊嚴其岸，栴檀妙香普散其中，優鉢羅華、波頭摩華、拘物頭華、芬陀利華及餘寶華皆悉遍滿，微風吹動，香氣遠徹，華林寶樹周匝圍遶。
When those four great rivers have poured out, they all together circle the great lake seven times, and then divide and flow away in their four directions, surging and racing until they enter the great ocean. In the turnings of those rivers, in the spaces between them, there are utpala lotuses, padma lotuses, kumuda lotuses and puṇḍarīka lotuses made of heavenly jewels, giving off rare fragrance, their wondrous colours pure; their many petals and leaves and their many pistils and stamens are all of jewels, translucent of themselves, and all of them send forth radiance and shine into one another. The Heatless Lake is fifty yojanas around; its bed is spread throughout with fine sand of every jewel; it is ornamented with maṇi of every kind; measureless fine jewels adorn its banks; the fragrance of sandalwood is scattered everywhere through it; utpala, padma, kumuda and puṇḍarīka lotuses and other jewel-flowers fill it entirely; and when a light breeze stirs them their scent carries far, while groves of flowering trees and jewel trees surround it on every side.
無熱惱大龍王 — the great nāga king Anavatapta, the Heatless. The name is translated in the Chinese rather than transliterated, and it carries the point of the whole simile: a source that never gets hot. Part 484 used the same lake for the four rivers that never run dry; here the sūtra stops to describe it.
各共圍遶大池七匝 — they all together circle the great lake seven times. The rivers do not simply leave. Before crossing a continent they go around their own source seven times, which is the detail a reader would not invent and which makes the geography feel reported rather than devised.
Part 524 Complete
This continues chapter twenty-seven, 十定品, The Ten Concentrations, in fascicle forty-two. Part 525 gives the sunlight on that lake — every grain of sand and every jewel showing the sun's disc, and each reflection appearing again in all the others — matched to a bodhisattva in this samādhi, in whom every samādhi is seen within every other.