化龍池 The Pool Where Dragons Are Made
長老四眾，俱各叩頭謝恩。馬亦謝恩訖。仍命揭諦引了馬，下靈山後崖化龍池邊，將馬推入池中。須臾間，那馬打個展身，即退了毛皮，換了頭角，渾身上長起金鱗，腮頷下生出銀鬚，一身瑞氣，四爪祥雲，飛出化龍池，盤繞在山門裡擎天華表柱上。諸佛讚揚如來的大法。长老四众，俱各叩头谢恩。马亦谢恩讫。仍命揭谛引了马，下灵山后崖化龙池边，将马推入池中。须臾间，那马打个展身，即退了毛皮，换了头角，浑身上长起金鳞，腮颔下生出银须，一身瑞气，四爪祥云，飞出化龙池，盘绕在山门里擎天华表柱上。诸佛赞扬如来的大法。
逐句解 Line by line
The elder and his three all knocked their heads on the ground and gave thanks for the favour.
叩頭謝恩 — the formula for accepting an imperial gift, and the Tang monk has used it three times already this chapter in front of Taizong. The same words, the same bow, in front of the Buddha. Heaven and the Tang state take thanks in identical language.
The horse gave thanks for the favour too, and it was done.
⚠ Six characters, and they are quietly perfect. The horse bows as well. 訖 — finished, concluded. It is a clerk's word, the one stamped at the foot of a completed document, and it closes the investiture.
He ordered the Guardians as before to lead the horse down to the edge of the Dragon-Making Pool, on the cliff behind the Spirit Mountain, and push him into the water.
⚠ 化龍池 — the pool for turning into a dragon. It exists, on the Spirit Mountain, behind the cliff; nobody has mentioned it in ninety-nine chapters and it is apparently standard equipment. ⚠ 推入池中 — pushed him in. Not led, not invited: shoved. It is exactly what Monkey did to his master at the Cloud-Touching Crossing two chapters ago, and it produced the same kind of result.
In a moment the horse gave himself a stretch, shed his hide, exchanged his head for a horned one, grew golden scales the length of his body and silver whiskers under his jaw, with an auspicious vapour about him and lucky clouds at his four claws; and he flew out of the Dragon-Making Pool and coiled himself round the sky-propping ornamental pillar inside the mountain gate.
⚠ The longest single sentence in the chapter, and it is a transformation shot: shed the hide, change the head, grow the scales, sprout the whiskers, out of the water and up the pillar. 長起金鱗 — grew golden scales. Here the character is zhǎng, to grow — the same graph that reads cháng, long, in the name of Chang'an and zhǎng, elder, in the Tang monk's title. ⚠ 華表柱 — the ornamental columns that stand outside a Chinese palace or tomb, carved with a coiling dragon. So the horse becomes a dragon and immediately arranges himself into the standard decorative position. The joke is silent and it is the only one in the passage.
All the buddhas praised the great Law of the Tathagata.
Eight characters, and the transformation is over. The assembly applauds and the scene closes. Nobody says goodbye to the horse.
The horse bows too. Six characters, and they are quietly perfect: the horse gave thanks for the favour too, and it was done — closed with a clerk's word, the one stamped at the foot of a finished document.
⚠ Then he is led to a pool behind the mountain and pushed in. Not led, not invited: shoved. It is precisely what Monkey did to his master at the Cloud-Touching Crossing two chapters ago, and it produces the same kind of result. The pool is standard equipment, apparently, and nobody has mentioned it in ninety-nine chapters.
⚠ What follows is the longest sentence in the chapter and it is pure transformation: shed the hide, change the head, grow the scales, sprout silver whiskers, and out of the water. And then he coils himself round the ornamental pillar inside the mountain gate — which is exactly where a carved dragon goes on a Chinese palace column. He becomes a dragon and immediately takes up the standard decorative position.
The assembly applauds the Law and the scene ends. Nobody says goodbye to him.