_shuai-jan_ is a snake that is found in the Ch‘ang mountains.
["_Shuai-jan_" means "suddenly" or "rapidly," and the snake in question
was doubtless so called owing to the rapidity of its movements. Through
this passage, the term in the Chinese has now come to be used in the
sense of "military manœuvers."]
Strike at its head, and you will be attacked by its tail; strike at its
tail, and you will be attacked by its head; strike at its middle, and
you will be attacked by head and tail both.