Hermes was an Olympian god of travel, trade, diplomacy, persuasion, writings and athletics. He was also the messenger of gods because he could moved freely and fast between the worlds of mortal and divine. Many thought of him as the protector of heralds, merchants, travellers and even thieves. Hesiod and Homer thought of him as the inventor of skilled or deceptive acts. The god was also said to be a personal agent of Zeus, helping him in numerous occasions. He had also done many deeds for other gods and semi-gods.
Most of the time, he is depicted as an athletic beardless young man, wearing winged sandals and winged helm. He is also holding his staff with snakes wrapped around it, with which he could deceive or persuade anyone. Sometimes, he is holding a wand instead of staff but with the same characteristics. And on some occasions, he is even depicted as a fully grown man with a beard.
Hermes was a son of Zeus and Maia, a daughter of Atlas. He was born in a cave near Mount Cyllene in Arcadia and in the first hours after his birth, in a myth of Apollo's cattle, he went to Pieiria and stole some oxen which Apollo was tending there. To prevent from being discovered by tracks, he put boots on cattle's feet and led them to Pylos. He sacrificed two, pinned up their hides on rocks, boiled some of the juicy meat for his meal and burned the rest what was left of these two oxen. From the tortoise-shell that he found there, while having a meal, he made a lyre with binding strings made from cattle across the shell and also a plectrum for the lyre. Meanwhile, Apollo was already searching for his cattle in Pylos, asking locals for their whereabouts. The locals told him to search for a boy with cattle that they had seen passing through. When Apollo finally found him and the cattle, he heard the magnificent sounds of the instrument and was willing to trade some of the cattle for it. They made the exchange and soon after, while Apollo was tending the rest of his flock, Hermes fashioned a shepherd's pipe for his instrument to play. It was not long before Apollo become enthusiastic over the pipe and offered him his golden staff that he carried when tending his herd. But this time, Hermes wanted in exchange, not only the golden staff, but also a proficiency in the art of prophecy. Apollo was eager to get the pipe and therefore he agreed on giving him the staff and the lesson. Hermes and Apollo became friends and Hermes promised him never to steal anything from him again. Zeus was impressed with Hermes' persuaiton and bartering skills and appointed him as his personal messenger.
Wrath of Hermes
There is more to the previous story in myth where a local named Battus lived on the top of the hill from where the cattle of Apollo were stolen. He heard the herd when they were being driven past his house and therefore he came out and found out that they were being stolen. However, he agreed not to tell anyone in exchange of reward and Hermes did promise him a reward on these terms. Then Hermes went to hide his cattle inside a cave by the cliff near Koryphasion and came back to Battus transformed into another person to test his oath. He offered him a robe, if he could tell of noticing a herd of cattle being driven past his house. And Battus took the robe and told him about the cattle. Hermes was furious to be lied to and so easily double crossed and therefore turned the man into a stone statue with his wand.
Rescuing Io, mistress of Zeus
In the myth of rescuing Io, Zeus asked Hermes to save his mistress Io whom Zeus himself had an affair with and was forced to instantly turn her into a cow, to hide her from his approaching wife that was looking for her pristess. When Hera saw Zeus with a cow, and heard his lame excuse, she was rightfully suspicious and demanded to give her the animal as a gift. Zeus had no choice but to agree because, otherwise, his secret would be disclosed. Hera then called her servant Argos, the hundred-eyed giant, to take her away from Zeus and keep an eye on her. Argos had one hundred eyes and never had to close them all while sleeping and was the perfect guard for this task. However, Hermes was able to make the giant fall asleep with the soft tunes of his pipe. When the giant's nap turned into slumber, Hermes picked his sword and chopped off his head because he didn't want to leave any witnesses. And poor little Io was finally free, but still a cow. She roamed mile after mile for many years until she reached Egypt and gave birth. Then Hera finally released her from torment as, being the goddess of childbirth, she felt pity for Io.
Hermes was also involved in many myths of other gods or semi-gods. For instance, he helped saving Dionysus, rescued Asclepius, a son of Apollo, at his birth and helped Perseus in his quest to defeat Medusa. He also helped Odysseus, giving him a potion that prevented Odysseus to fall under the spell of Circe as well as saving him from captivity of nymph Calypso. In the myth of twelve labours of Heracles, he helped the hero to deceive the Cerberus and consequently bringing the beast from the underworld and completing his quest.