變作海東青 He Becomes A Falcon
這大聖收了金箍棒，捻訣念咒，搖身一變，變作一個海東青。颼的一翅，鑽在雲眼裡，倒飛下來，落在天鵝身上，抱住頸項嗛眼。那牛王也知是孫行者變化，急忙抖抖翅，變作一隻黃鷹，返來嗛海東青。这大圣收了金箍棒，捻诀念咒，摇身一变，变作一个海东青。飕的一翅，钻在云眼里，倒飞下来，落在天鹅身上，抱住颈项嗛眼。那牛王也知是孙行者变化，急忙抖抖翅，变作一只黄鹰，返来嗛海东青。
逐句解 Line by line
The Great Sage put away his gold-banded rod, made the sign and said the spell, shook himself and changed into a gyrfalcon.
He opens the contest with the finest hunting bird in the empire. 海東青 is the white gyrfalcon of the north-east, the most prized raptor under the Ming and taken as tribute from Jurchen country — reserved in practice for the court. Not a monster: a status symbol. (一 shifts to yí in 一變, before the falling tone of 變.)
With a whirr of one wing he bored up into a rift in the cloud, flew back down inverted, dropped on the swan's body, gripped its neck and took at its eye.
Every clause here is what a falcon actually does to a swan. 嗛 is xián and not qiǎn, at this site and the next alike — the reading settled seven passages ago at 小雁兒嗛了眼睛, where the proverb had a gosling carry off a fowler's eye; the lexicographers gloss that band as 口有所銜也, to hold in the mouth, and illustrate it with a line about birds carrying flesh in the beak. Here the illustration has become the scene. 倒 is dào, upside down.
The Bull King knew it for Pilgrim Sun's transformation, shook out his wings in haste and changed into a yellow hawk, turning back to take at the gyrfalcon.
The mirror of the line before: the bird that was seized now seizes. The chase is built on exactly this kind of reversal, each transformation answering the last with the creature that preys on it.
The transformation contest opens with the finest hunting bird in the empire. The 海東青 is the white gyrfalcon of the north-east, taken as tribute from Jurchen country and reserved in practice for the court, and the Great Sage picks it rather than anything monstrous. The chase will run through twelve shapes, and it begins as falconry.
The attack is described with real precision — up into a rift in the cloud, back down inverted, onto the body, the neck gripped, the eye taken. Every clause is what a falcon actually does to a swan, and the novel is content to let a supernatural contest be an accurate one.
嗛 is the character that carries the eye-taking, and it has been in this chapter before. Seven passages ago the Great Sage said of himself that a gosling had carried off his eye, using this same word; the dictionaries gloss it with a line about birds taking flesh in the beak. The proverb has turned into the thing it described — with the Great Sage now on the other end of it.