Exodus 7:9

When Pharaoh shall speak unto you, saying, Shew a miracle— Hence it appears evidently, that miracles were judged, by the common sense of mankind, a proper and sufficient proof of a commission from God. Our Saviour constantly made this appeal: believe me for the work's sake:—the works which I do, they witness for me, &c. Grotius has an ingenious conjecture on this place, that the custom of ambassadors bearing a caduceus or rod in their hands, was first derived from this event to the neighbouring nations; and from them to the Greeks and Romans: and it is remarkable, that the caduceus of Mercury, the messenger of the gods, was formed of two serpents twined round a rod.