Text[]
Haiyao Bencao, ch. 4[]
Chinese original[]
又按通天犀，胎時見天上物命過，並形於角上，故云通天犀也。欲驗於月下，以水盆映，則知通天矣。
English translation (James Hsü, 1999)[]
The tongtianxi, during the time of pregnancy, beholds the forms of things passing across the sky, and these are reproduced in the horn of the embryo: hence the designation tongtianxi. When the horn, placed in a water-basin during a moonlit night, reflects the brilliancy of the moon, it is manifest that it is a genuine tongtianxi horn.