Acts 14:12

And they called Barnabas, Jupiter; and Paul, Mercurius Of course this was not known until afterwards, and St Luke in his narrative, as a Greek, gives the Greek names of the gods, Zeusand Hermes. We can understand how the heathen people concluded that if any deity came to visit them with a beneficent purpose it would be that god Jupiter whose temple was before their city and to whom therefore their chief worship was paid; and Mercury was counted as the principal attendant on Jupiter, and moreover as the god of eloquence. It was obvious, therefore, to assign that name to the chief speaker, and the name of Jupiter to that one of the two Apostles who had the more commanding presence. That St Paul was not such a figure we know from his own words, and tradition describes him as "little in height, with a bald head and crooked legs" (Acta Apocryph. p. 41, Tischendorf).

because he was the chief speaker Literally, "the leader of the speech." This character is always assigned to Mercury by the heathen writers, and almost the very words of the text are used of him by Iamblichus, de Myst. ad init.