Hyacinthus was born in Amyclae, a town in the fertile valley of the Eurotas River in Laconia, the region of the Peloponnese dominated by the city of Sparta. His father was Amyclas, the eponymous king from whom the town took its name, a descendant of Lacedaemon, the son of Zeus and Taygete, one of the Pleiades, the seven sisters who were transformed into stars. His mother was Diomede, a woman of the Spartan royal house. Hyacinthus grew up in a land of harsh discipline and austere beauty, where boys were trained for war from the age of seven and where the arts of music and poetry were cultivated with the same rigour as the arts of combat. He was beautiful beyond any other youth in Laconia, with hair the colour of dark honey and eyes that caught the light like the pools of the Eurotas, and his beauty attracted the attention of a god.

Apollo, the Olympian god of light, music, prophecy, and archery, saw Hyacinthus and desired him. The god descended from Olympus and came to Amyclae in the guise of a wandering musician, but his disguise was unnecessary. Hyacinthus recognised the god and welcomed him, and the two became inseparable. Apollo taught the youth to play the lyre, the seven-stringed instrument whose music could charm beasts and soothe the Furies, the avenging spirits who pursued murderers. He taught him to hunt with the bow, to throw the discus, and to drive the chariot, and he gave him the gift of prophecy, the power to see the future that was Apollo's own special domain. Hyacinthus learned quickly, and his skill was so great that the Spartans said he would one day surpass his teacher, a boast that made the god smile with pride rather than jealousy, for Apollo loved the boy without reservation.

But Apollo was not the only one who loved Hyacinthus. Zephyrus, the west wind, the gentle breeze that brought the spring rains and the first warmth of the year, had also seen the youth and desired him. Zephyrus was a god of lesser rank than Apollo, one of the Anemoi, the four winds who served the greater gods, and he knew that he could not compete with the Olympian for Hyacinthus's affection. He watched in secret as Apollo and Hyacinthus played together on the plain of Amyclae, throwing the discus back and forth, racing their chariots, and singing to the lyre, and his jealousy grew with every day. Zephyrus was not a violent god by nature, but love unrequited can turn even the gentlest spirit to malice, and the west wind began to plot a revenge that would cost him nothing but would destroy everything Apollo loved.

The tragedy struck on a day of perfect spring weather, when the sky was clear and the Eurotas ran full with melted snow from Mount Taygetus. Apollo and Hyacinthus had gone to the plain to practise the discus throw, a sport in which a heavy circular stone or metal disc was hurled for distance. Apollo threw first, and his discus soared into the sky, catching the sunlight as it spun, and Hyacinthus ran to catch it on its return, laughing with the joy of the game. Apollo threw again, harder this time, and the discus flew further than any mortal could have thrown it. Hyacinthus ran to meet it, his eyes on the spinning disc, but Zephyrus, watching from his invisible place in the air, blew a sudden gust across the plain. The wind caught the discus and deflected it from its path, sending it straight toward the running youth. It struck Hyacinthus in the head with a sound like a cracked bell, and he fell to the earth, his skull shattered, his blood pouring onto the Spartan soil before Apollo could reach him.

The god's grief was absolute. Apollo knelt beside the body and tried to staunch the wound, pressing his hands against the boy's forehead, but the injury was mortal and no god could reverse death once it had taken hold. Apollo wept, and his tears fell upon the blood that soaked the ground, and from the mingled tears and blood there sprang a flower, the hyacinth, whose petals were dark red and bore the marks of the Greek letters AI AI, the cry of lamentation that means "alas, alas." The Spartans said that the flower bloomed every spring on the anniversary of Hyacinthus's death, and that its scent was the scent of divine grief. Apollo cursed Zephyrus for his treachery, and the west wind was banished from the company of the gods, condemned to wander the earth as a bringer of storms rather than gentle breezes.

The cult of Hyacinthus at Amyclae was one of the oldest and most important in Sparta. His tomb lay beneath the colossal bronze statue of Apollo that stood on the Throne of Apollo, a monument so ancient that the Spartans could not remember who had built it. Every year the Spartans celebrated the Hyacinthia, a three-day festival that began with mourning and ended with rejoicing. On the first day, the people wore black and fasted, and no music was played. On the second day, sacrifices were offered at the tomb, and choirs of boys sang hymns of lamentation. On the third day, the mourning was cast aside, and the Spartans celebrated with athletic contests, processions, and banquets, for Hyacinthus was not merely a dead youth but a vegetation god, a spirit of the spring who died with the old year and was reborn with the new. The festival thus combined grief for his death with joy at his return, and it remained one of the most important religious observances in Laconia until the end of antiquity.