The Great Serpent Bristled Like a Boar, Sounding Like a Watchman's Clapper
The first guideway of the Northern Mountains records Daxian Mountain: no plants grow there, jade lies below, and the mountain itself is four-square and impossible to climb. On it lives a serpent called simply the changshe, the Long Snake. Its body is covered in stiff bristles like the hairs of a boar, and its voice is the knock of the wooden clapper a night watchman beats on his rounds — a dry, measured tapping from a mountain no one can ascend.
The text gives no measurement; the commentators supplied one. Guo Pu's fourth-century annotation cites an older tradition that the snake is 'a hundred xun long' — at eight chi to the xun, eight hundred chi, close to two hundred metres. A furred snake already defies nature; the clapper-like knocking and the unclimbable square mountain give the entry a horror of distance, a thing heard rather than seen. The classic never even says it harms anyone. It simply places it there.
Later writers on giant serpents regularly cited this passage as an early authority. The phrase 'long snake' also grew a figurative life: the Zuozhuan already pairs it with the great boar in 'fengshi changshe', a byname for rapacious states that swallow their neighbours, and that metaphor circulated alongside the literal bristled monster of Daxian Mountain.
