The Thyrsus was born in the mountains of Nysa, the hidden place where the infant Dionysus was raised after his mother Semele was consumed by the thunderbolt of Zeus. Semele had been a mortal princess of Thebes, the daughter of King Cadmus and the goddess Harmonia, and she had lain with Zeus, the king of the gods, who had visited her in the form of a mortal man. When Hera, the queen of Olympus and wife of Zeus, discovered the affair, she tricked Semele into demanding that Zeus show her his true divine form, and the sight of his thunder and lightning burned her to ash. But Zeus saved the unborn child by sewing him into his own thigh, and when Dionysus was born a second time, he was already divine. The god Hermes, the messenger whose winged sandals carried him across the world in hours, took the infant to the nymphs of Mount Nysa, who raised him in secret among vines and ivy and taught him the secrets of wine.

Dionysus grew to manhood in the wild places, and the thyrsus was his first and constant companion. It was a simple thing: a tall stalk of fennel, hollow and light, topped with a pine cone and wreathed in ivy leaves and vine tendrils. But in the god's hand it was a weapon of transformation. With a touch of the thyrsus, water turned to wine. With a wave, vines burst from the earth and wrapped around stone columns. With a strike, the boundaries between man and beast, waking and dreaming, life and death, dissolved like mist in the sun. The thyrsus was not a club, though it could be used as one. It was not a spear, though it could be thrown. It was the physical form of ecstasy itself, the staff that carried the god's power to unmake the world and remake it in his own image.

The thyrsus appears most terribly in the story of King Pentheus of Thebes, the grandson of Cadmus and the cousin of Dionysus himself. Pentheus had inherited the throne of Thebes from his father Echion, one of the Spartoi, the Sown Men who had sprung from the teeth of the Dragon of Ares, and he ruled with a stern hand. When Dionysus returned to Thebes to establish his worship, Pentheus refused to recognise the new god. He imprisoned the Bacchic revelers, mocked the Maenads, and declared that no foreign deity would be worshipped in his city. Dionysus, in disguise, was arrested and brought before the king, but he escaped his chains with a touch of the thyrsus and walked free. Then he took his revenge.

He drove the women of Thebes mad, including Pentheus's own mother Agave and his aunts Ino and Autonoe, and led them to Mount Cithaeron, the mountain that rose above the city. Pentheus, determined to spy on the rites and expose them as debauchery, climbed the mountain in disguise, wearing a woman's dress and hiding in a tree. But Dionysus saw him. The god touched the tree with his thyrsus, and the branches bent and lowered Pentheus to the ground, where the Maenads fell upon him. Agave, his own mother, led the attack. She seized his arm and tore it from the socket. Ino ripped off his other arm. Autonoe tore at his flesh. The women beat him with their thyrsuses, the fennel-rods splintering against his body, and in their frenzy they did not recognise their own king. Agave lifted his severed head on her thyrsus and carried it down the mountain, believing it was the head of a lion she had killed in the hunt. The thyrsus had turned a mother into a murderer and a king into prey.

The thyrsus appears again in the story of the Tyrrhenian pirates, the sailors who tried to kidnap the god. Dionysus was walking on the shore of the island of Icaria when he saw a ship, and the sailors, not recognising him for a god, seized him and bound him with ropes. But the ropes fell from his limbs like threads, and the helmsman, seeing the miracle, warned his companions that they had captured a god. They did not listen. Dionysus smiled and touched the mast of the ship with his thyrsus. Vines burst from the wood, heavy with grapes, and ivy wrapped around the oars. Wine flowed across the deck, and the air filled with the sound of flutes and cymbals. The pirates, terrified, leaped into the sea, and Dionysus turned them into dolphins, the first of their kind, who still leap and sport in the waves. The thyrsus had transformed a ship of kidnappers into a floating vineyard and then into a school of fish.

In the later epic tradition, particularly in the Dionysiaca of Nonnus, the thyrsus became the standard of Dionysus's armies as he marched across India and the East, conquering kingdoms not with swords but with wine and ecstasy. The god led a host of satyrs, the half-man half-goat creatures who were his constant companions, and Maenads, the frenzied women who had abandoned their homes to follow him, and his thyrsus was their banner. Where he struck the earth with it, springs of wine gushed forth. Where he waved it over an army, the soldiers dropped their weapons and danced. The thyrsus was the weapon of a conqueror who needed no walls to breach and no armies to defeat, for his power was the power to make men forget why they fought.

In Athens, the thyrsus became the symbol of the theatre. Dionysus was the patron of drama, and the great festivals of tragedy and comedy were held in his honour. The actors carried thyrsuses in the satyr plays, the bawdy comedies that followed the serious tragedies, and the staff became the emblem of the actor's craft, the transformation of one person into another. The thyrsus was the wand that turned a man into a god, a woman into a beast, and a sober citizen into a reveler, and the theatre was the place where those transformations were made safe. The god of ecstasy gave the Greeks their greatest art, and the thyrsus was its badge.