遇土而入 It Sinks into the Earth
遇土而入者，大聖方才打落地上，他即鑽下土去了。這個土有四萬七千年，就是鋼鑽鑽他也鑽不動些須，比生鐵也還硬三四分，人若吃了，所以長生。大聖不信時，可把這地下打打兒看。」行者即掣金箍棒築了一下，響一聲，迸起棒來，土上更無痕跡。行者道：「果然，果然。我這棍打石頭如粉碎，撞生鐵也有痕，怎麼這一下打不傷些兒？這等說，我卻錯怪了你了，你回去罷。」那土地即回本廟去訖。遇土而入者，大圣方才打落地上，他即钻下土去了。这个土有四万七千年，就是钢钻钻他也钻不动些须，比生铁也还硬三四分，人若吃了，所以长生。大圣不信时，可把这地下打打儿看。」行者即掣金箍棒筑了一下，响一声，迸起棒来，土上更无痕迹。行者道：「果然，果然。我这棍打石头如粉碎，撞生铁也有痕，怎么这一下打不伤些儿？这等说，我却错怪了你了，你回去罢。」那土地即回本庙去讫。
逐句解 Line by line
"As for meeting earth and sinking in — the moment you, Great Sage, knocked it to the ground, it bored straight down into the soil.
And the answer to the mystery, delivered as an afterthought. It met earth, so it went into the earth. 鑽下土去, bored straight down. 方才, fāng cái, just now.
This soil is forty-seven thousand years old; a steel drill could not bore into it a hair's breadth — it is harder than wrought iron by three or four degrees. That men live long from eating the fruit is owing to this.
The soil is a marvel in its own right, and the Earth-God's explanation runs backwards from what you might expect: it is not that the fruit makes the soil extraordinary, but that this forty-seven-thousand-year-old ground is why the fruit confers long life. The number is the same as the lifespan a single fruit grants — the tree and its soil are the same age as the gift they give. 鋼鑽 takes 鑽 as zuàn, the noun, a drill; the two that follow are the verb zuān, to bore. 還硬三四分, harder by three or four 分, fēn — degrees on a notional scale. 所以長生 takes 長 as cháng, "long life."
If you do not believe it, Great Sage, give the ground here a rap and see."
打打兒, dǎ dǎ er — give it a rap, with the diminutive er softening the imperative. The Earth-God is inviting the most destructive being present to hit the ground, which shows some confidence.
Pilgrim at once drew his gold-banded staff and struck the ground once; with a clang the staff sprang back, and there was not a mark on the soil.
And nothing happens. 金箍棒, the gold-banded cudgel, which weighs thirteen and a half thousand catties and once propped up the Milky Way. 迸起棒來, the staff sprang back off the surface.
Pilgrim said, "True enough, true enough.
果然, doubled — Pilgrim conceding a point, which he does about once a chapter.
This staff of mine smashes stone to powder and dents even wrought iron — how did this one blow not so much as scratch it?
He measures the marvel against his own instrument, which is how he measures everything: this staff powders stone and dents wrought iron. 些兒 takes the er suffix.
Then it is as you say — I wrongly blamed you. You may go back."
And then the rare thing: an apology. 錯怪了你了 — I blamed you wrongly. Two 了 in four characters, the first completive, the second final.
And the Earth-God went straight back to his shrine.
去訖, qù qì, departed — a slightly formal closing verb, giving the small god a dignified exit.
The answer arrives almost as an afterthought: it met earth, so it went into the earth, and the ground here is not ordinary ground. Forty-seven thousand years old, harder than wrought iron, impervious to a steel drill. Note the number — it is exactly the lifespan one fruit confers. The soil and the gift are the same age, and the Earth-God's causation runs in the direction one might not expect: the fruit gives long life because of the soil, not the other way round.
Pilgrim tests it in the only way he knows, with the gold-banded staff that powders stone and dents iron, and the staff bounces off without leaving a mark. Then he does something he does perhaps once a chapter: he apologises. I blamed you wrongly; you may go. The small god withdraws to his shrine with his dignity intact, and the mystery of the vanished fruit is closed — leaving Pilgrim in possession of the one thing he was missing, which is the method.