Leto on Delos
Hera's watchers drive the laboring Leto from every shore.
Zeus next laid eyes on the "dark-gowned Leto," daughter of the Titaness Phoebe (prophetic wisdom) and the Titan Coeus (analytical intellect).
Hesiod describes Leto as "kindhearted to both men and gods, mild from the beginning, gentlest in all Olympos."
Zeus was enchanted by Leto and by her equally modest sister Asteria, mother of Hecate and goddess of the falling stars.
Asteria escaped Zeus's lust by leaping into the sea, transforming herself into the Greek island of Delos. Meanwhile, her sister Leto got pregnant by Zeus and became the new target of Hera's wrath.
In the following "Hymn to Delos," Callimachus describes how Hera kept watch, ensuring that Leto was denied any land on which to give birth…
Callimachus
Hera kept watch in the heavens, her heart swelling with unspoken rage, and she sought to hinder Leto, who was held fast in the pangs of childbirth. She set two watchers to guard the earth: Ares and Iris.
Ares, seated in arms upon the high crest of Mount Haemus, surveyed the wide continents, while his steeds were stalled by the seven-chambered cave of Boreas, the North Wind.
Iris, seated upon Mimas, hastened to the far-scattered isles. There they sat, threatening all the cities that Leto approached, and forbidding them to grant her shelter.
The lands of Arcadia fled Leto; the aged city of Pheneios fled, and all the land of Pelops. Aonia also fled, as did the springs of Dirke and Strophia.
Only Asteria, lover of song, beheld Leto’s suffering. She welcomed her sister ashore.
Leto gladly ended her weary wandering, sat beside the stream of Inopos, loosed her girdle, and leaned her shoulders back against a palm tree, while sweat poured over her flesh like rain.
Hera, Lady of heavy wrath, did not remain long without tidings, for swift Iris sped to her. Still panting, with words mingled in fear, she spoke:
Iris
O Hera, most excellent among goddesses—Leto looses her girdle within an island. All others rejected her, but Asteria called her by name. Asteria—that scum of the sea, as you well know…
Hera (juno)
So now, shameful mates of Zeus, may you all wed in secret and give birth in darkness—not even where poor mill-women labour, but where the sea-seals bring forth, amid desolate rocks.
Yet against Asteria I am not utterly angered. She has wronged me in granting Leto favour, but I still honour her—for she did not desecrate my bed, but chose the sea instead of Zeus.
Leto gave birth to twins, becoming the goddess of motherhood and protector of children. Delos, once barren and wandering, immediately sprung to life.