The Heliades belong to the family of the sun. Their father Helios, son of the Titans Hyperion and Theia, drove the flaming chariot that brought light across the sky each day. Their mother was Clymene, one of the three thousand daughters of Oceanus and Tethys, or in Aeschylus' tragedy the Oceanid Rhode. Their brother was Phaethon, whose name means Shining One. Phaethon grew up in the palace of Merops, king of Ethiopia, and came to doubt that Helios was truly his father. His mother sent him east to seek the god. Helios welcomed him and, promising proof of paternity, swore an oath he would regret. Phaethon asked to drive the sun chariot for a single day.

The ride destroyed the order of heaven and earth. The horses sensed the weakness of their driver and left the road of the sun. Phaethon carried the chariot too close to earth, scorching cities, forests and fields, then too far away, freezing regions beneath the cold of heaven. The constellations burned. Libya's landscape was blackened. The earth cried out to Zeus for rescue. To save the cosmos, the king of the gods hurled his thunderbolt. Phaethon fell from the burning chariot, half consumed by fire, and struck the waters of the River Eridanus at the western edge of the world. The shock left a deep, steaming lake. His body smouldered below the surface, and no bird could fly safely across the rising vapour.

His sisters came to the river. The fullest accounts call them Aegle, Lampetia and Phaethousa, names of light: Radiance, the Shining One and the Shining Brightly. Aeschylus may have made these three daughters of Helios and Rhode. Other traditions counted five or seven. Hyginus preserves seven Hesiodic names: Merope, Helie, Aegle, Lampetia, Phoebe, Aetherie and Dioxippe. Some were already known from other solar families, including Homer's daughters of Neaera who guarded the cattle of Helios on Thrinacia. The stories overlapped and blended until the daughters of the sun became one grieving company. Their collective name, Heliades, simply declared that they were children of Helios.

For four months the sisters remained beside the river. They did not return home, eat or dress their hair. Their brother's grave was also the place where the world had caught fire, and their grief joined the two catastrophes. Ovid describes their cries and laments beating against the smoky bank. When they tried to move at last, their feet would not leave the ground. Roots broke from their toes and dug into the earth. Bark crept over their shins, thighs, breasts and faces. Their fingers stretched into branches. Their hair became poplar leaves.

Their mother Clymene came to the river and tried to save them. She pulled at the bark, snapped the young branches and tore away pieces of their bodies, only to find living flesh beneath. The sisters cried out through their half-formed mouths. Each strip of bark hurt them like skin being pulled from living bone. They begged her to stop. Clymene had already lost her son to fire and now she watched her daughters disappear into wood. The transformation was neither immediate nor gentle. The maidens remained half sisters and half trees as the bark climbed past their waists and shoulders.

Zeus transformed them from pity. In one version the god looked down upon their inconsolable mourning and changed them so that grief itself could cease to torment their bodies. Another version preserved by Hyginus makes the punishment their own responsibility: they had yoked the horses of the sun for Phaethon without their father's permission. Either way, the sisters became black poplars, trees whose bark trembles and whose leaves turn their silver undersides to the wind. Their voices did not vanish. They became the mournful rustling of leaves over water.

Their tears continued to fall. Golden drops welled from their eyes, caught the light and hardened as they descended. Ovid calls their tears electrum, the gleaming substance of amber. Some drops fell on their cheeks, others onto their breasts, and many rolled down the bark into the river. When the sun dried the bank, the drops became small hard stones. Storms gathering along the Eridanus swept the tears into the stream and carried them towards the sea. In Apollonius of Rhodes, the Argonauts sail past Phaethon's lake on their return journey and hear the shrill lament of the Heliades. Amber drops shine on the sand around them. The wind rises, the dark water overflows and the collected tears are swept into the river. The sailors hear the trees but do not see the faces of the sisters.

The myth made grief a substance. The Greek word for amber, elektron, was close to Elektor, an epithet of Helios as the radiant one, and the warm golden surface of amber seemed like sunlight caught in solid form. The word for tear, dakryon, could also mean sap or gum. The Heliades became a natural explanation for both: poplars wept drops that hardened into amber, and the daughters of the sun wept a form of captured light. Diodorus says the poplars dripped these golden tears at the same season each year. Philoxenus, another early poet, had the Heliades change into poplars in their grief and shed amber beside the Eridanus annually. Amber therefore belonged to mourning. Diodorus notes that the stone was used above all in the funeral rites of the young, the people whose loss Phaethon's story made unbearable.

Aeschylus gave the sisters a tragic stage. His play called the Heliades has almost entirely vanished, but a few lines and summaries survive. The daughters of the sun gathered around the death of their brother and learned what the fragment calls a new way of mourning. Aeschylus placed the fall of Phaethon in Iberia and may have moved the Eridanus towards the Rhone rather than the Po. The surviving words are enough to show that the weeping chorus stood at the centre of the drama. Euripides also wrote a Phaethon that differed from the older treatment, and his Hippolytus remembers the Heliades shedding amber tears for their brother by the river. The Greek stage turned one cosmic disaster into a lament sung by the women who were left behind.

Later writers followed different paths around the same river. Apollonius sends the Argonauts through a northern landscape haunted by steam, stench and sound. Diodorus places the fall at the mouth of the river later called the Po and explains the amber through the grief and transformation of Phaethon's sisters. Strabo dismisses the stories of the Eridanus, the amber islands and the poplar sisters as poetic invention, yet in doing so he preserves the full list of mythic features. Pausanias hears that the Eridanus flows through the land of the Gauls and that the daughters of Helios still lament Phaethon upon its bank. Quintus of Smyrna says that Helios himself turned their tears into amber so that the grief of his daughters would bring undying honour to their dead brother. In his Fall of Troy, mourners heap amber from the Heliades upon the funeral pyres of Achilles and Ajax.

The sisters entered art as figures caught between forms. Philostratus imagines a painting in which their toes already have roots, their waists are tree trunks and their arms are branches. Their hair has become poplar leaves. Their tears shine in their eyes, glisten on their cheeks and turn to gold as they trickle down their breasts. The river god Eridanus opens his eddying arms to receive them. The scene makes transformation visible in stages: maiden, tree, jewel. Roman wall paintings and later Renaissance works repeated the sisters in the same suspended state, beautiful women merging into trunks while golden drops fall around them. An Urbino plate from the 16th century could identify the scene simply as Phaethon's sisters, and the image still showed the amber drops streaming from their eyes.

Their tears became objects of fascination because amber could hold death inside its beauty. Martial jokes about insects caught in Phaethonic drops: a bee sealed in amber seems to have chosen its own death as a reward; an ant becomes precious only after the stone has made its tomb; a viper trapped in a Heliadic tear receives a finer burial than Cleopatra. Quintus makes the tears part of heroic burial. The Greek belief joined a natural fact to a poetic one: insects, seeds and fragments of vanished life could be seen inside genuine amber. The Heliades' tears did not merely look golden. They preserved small fragments of the world.

The story also moved across myth as a measure of mourning. Nonnus compares the laments of Dionysus to the Heliades' song, and a Hamadryad nymph in his epic wishes to become one of them so that she too can weep amber beside the Eridanus. The dryad wants the permanence and public beauty of their grief even though her sorrow is different. Statius has the sisters wash the smoking Phaethon in the heated Po and says that a weeping grove rises by the river almost before his burial is finished. Valerius Flaccus remembers them weeping beside their father. Ovid makes them the permanent source of amber drops used for jewels, adornments and grave offerings. Their grief becomes a resource, carried by river, sea and trade to brides and mourners who never saw Eridanus.

Every version leaves the Heliades rooted beside the river. They do not receive a rescue, apotheosis or reunion. Their transformation does not end mourning; it gives mourning a form that can continue without exhaustion. Their bodies become a grove, their voices become leaves, their tears become jewels. The individual sisters lose their separate outlines and become a company of trees whose rustling is indistinguishable. The beauty of amber comes from that loss: golden light hardened by time, organic matter preserved within transparent stone, tears that travel farther than the mourners who shed them. The myth makes sorrow permanent without making it lifeless.

The Heliades' name eventually reached science through the word elektron. Greek writers knew that rubbed amber attracted light objects, and Thales of Miletus is remembered as the first to describe the phenomenon. The substance gave its name to electricity, the force hidden in what had once been thought of as frozen tears. The daughters of the sun weep a golden material that can draw invisible power from a surface. Their tears carry insects preserved for thousands of years, turning the myth of grief into a real image of the past held inside resin. No later theory cancels the poetic force of the older one. Amber remains warm, luminous and full of small worlds, and the Heliades remain the sisters whose sorrow first gave those properties a story.