《阴符》 / Yinfu Jing
《阴符》 / Yinfu Jing appears in 《资治通鉴·周纪》30丨苏秦的“开挂”人生 as the text 苏秦 studies after his first failures and family humiliation. The episode says Su Qin moves from broad reading to deep reading, choosing one short text as the basis for a practical breakthrough.
The source keeps the textual identity cautious. It says 《史记》 calls the work 《周书阴符》, while 《战国策》 calls it 《太公阴符之谋》. The host treats the later identification with 《六韬》’s short 《阴符》 chapter as less persuasive because that version mainly concerns military information signaling, whereas Su Qin’s breakthrough is 揣摩 in persuasion and political reading.