Literal meaning
cup (杯) — bow (弓) — snake (蛇) — shadow (影)
Origin
Book of Jin (《晋书·乐广传》). Yue Guang invited a friend to drink. The friend saw a snake in his cup and was horrified, but drank anyway out of politeness, then fell ill afterward. Yue Guang investigated and realized a painted bow on the wall had been reflecting in the cup. He invited his friend back, demonstrated the reflection, and the man's illness vanished on the spot. The phrase has been used since to describe paranoia about something that isn't actually a threat — or anxiety that the patient is curing themselves of, given the right reframe.
Examples
Usage & nuances
Used to dismiss someone's worry as unfounded. Slightly old-fashioned ring, but the imagery is striking enough that it's still in active use, especially in commentary about misplaced fear.
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