Mercurius is the Roman god of trade, gain and the market before he is anything else: his temple stood in the Circus Maximus, the merchants' guild kept him as patron, and the Ides of May was his day, when the dealers sprinkled their wares with water from his well. The herald's staff, the winged sandals and the office of guiding the dead came to him with the Greek Hermes, with whom he was identified early. He is the god of the deal and of the road the deal travels on.
Modern Practice
Mercurius is called on to open a market, to carry a message, and to keep a bargain honest in both directions. His practice is small and precise: the coin set aside, the word kept, the road walked.