《史记·七十列传·龟策列传》
为病人占卜时祝祷说： 现在某人病得厉害，如果必死，显出如此兆文：兆首上开，内外乱交错，兆身曲曲折折；如果死不了，现一个兆首上仰兆足收敛的兆文。 
卜占病者祝曰： 今某病困。死，首上开，内外交骇，身节折；不死，首仰足肣。 
When divining for a patient, pray and say: Now someone is seriously ill. If he must die, show such a sign: the sign is open, the inside and outside are intertwined, and the sign body is tortuous; if he does not die, show a sign of head up and feet closed.