Unlike many other creation stories, in the Greek versions the gods are created by the universe instead of the other way around. In the beginning, two entities exist, Heaven and Earth. Their children are the Titans, whose children, in turn, are the Olympians, the main Greek gods. The Titans—who include such notables as Ocean, Mnemosyne (Memory), and Prometheus, mankind's benefactor—rule the universe until Zeus and their other children conquer them.
The term "Olympians" comes from Mount Olympus, the gods' mystical home, which is conceived as a high mountaintop but is really a magical place that exists on a heavenly plane—not the heavens (which Zeus alone rules), earth, sea, nor underworld. Shared by all the gods, Olympus is perfect. Rain never falls there, and the gods while away their time eating, drinking, and listening to music. There are twelve proper Olympians: Zeus; his two brothers, Poseidon and Hades; his two sisters, Hestia and Hera (who is also his wife); his children, Ares, Athena, Apollo, Hermes, and Artemis; and two gods sometimes considered his offspring, Hephaestus and Aphrodite.
There are also lesser gods in Olympus, like Eros, the Graces, and the Muses. Several, like Hebe, goddess of Youth, are rarely mentioned in myths. There are also a few abstract forces personified, if not completely, who live on Olympus: Themis, Divine Justice; Dike, Human Justice; Nemesis, Righteous Anger; and Aidos, the sense of respect and shame that keeps humans from sinning.
Besides the Olympians, supernaturals also abound in the sea and underworld. Poseidon rules the sea, which is populated by the Nereids, sea nymphs who are distinct from the Naiads, the freshwater nymphs; Triton, the trumpeter of the sea; the shape-shifting Proteus, Poseidon's son or attendant; Pontus, a god of the deep sea; and Nereus, a god of the Mediterranean. There is a different god for every river, and the Titan Ocean—lord of the mysterious river that encircles the earth—lives there along with several other minor water gods.
Hades and his queen, Persephone, are the only rulers of the underworld—a place often simply referred to as Hades, after its king. A mysterious locale somewhere under the earth, it is the realm of the dead. Many myths concern a mortal's journey to the underworld and his encounters with its vicious guardian, the three-headed dog Cerberus. Divided into two sections, Tartarus and Erebus, Hades has five famous rivers: Acheron, the river of woe; Cocytus, the river of lamentation; Phlegethon, the river of fire; Styx, the river of the gods' unbreakable oath; and Lethe, the river of forgetfulness. A boatman named Charon ferries the dead from Erebus across the junction of the Acheron and the Cocytus to the gates of Tartarus, where they are judged by three former kings, Rhadamanthus, Minos, and Aeacus. The wicked are sentenced to eternal torment, while the good are admitted to the Elysian Fields, a place of perfect bliss. Other dwellers of Hades include the Furies and the personified forces of Sleep and Death.
Earth has its share of lesser gods as well. Pan and Silenus are mischievous and jovial earth gods. Pan rules over the Satyrs, a race of goat-men, and dances with the Dryads, the forest nymphs, and the Oreads, the mountain nymphs. Also on earth are the twins Castor and Pollux, sometimes spoken of as gods. The twins represent the ideal of brotherly devotion because, when an angry cattle-herder named Idas killed Castor, Pollux begged to die out of love for his brother. Rewarding this devotion, Zeus allows them to spend half the year in Hades and the other half on earth. Earth is also home to the wind gods: Aeolus, King of the Winds; Boreas, the North Wind; Zephyr, the West; Notus, the South; and Eurus, the East. The earth is also home to many other nondivine supernatural beings, such as the Centaurs—half-men, half-horses, one of whom is Chiron, an important tutor to many eventual heroes. Two trios of sisters are also earth-bound: the fearsome Gorgons, of which Medusa is one, and the Graiae, three ancients who share one eye. Finally, the Fates, who are assigned neither a place in heaven nor earth, spin, measure, and cut the threads of men's lives. The Fates are not subject to the decrees of any of the gods, not even Zeus himself.
With few meaningful changes, the Romans adopted much of Greek mythology, as their existing deities—the Numina, the Lares, and the Penates—were largely abstract, vague personifications of the processes of daily life. The most significant Numina were Janus and Saturn, who later represented the Greek Cronus, Zeus's father.
Aside from the twelve Olympians, there are two equally important gods who reside on earth: Demeter and Dionysus (Bacchus). These two are the best friends of humanity: Demeter, goddess of the harvest and nature, provides fruitful plenty and protects the threshing-floor, while Dionysus, god of wine and revelry, rules the grapevine and so the production of wine. Demeter is celebrated in a festival every fifth September; her prime temple is at Eleusis, and her worship is a central and mysterious aspect of ancient life. Bacchus also comes to be worshipped at Eleusis—a natural pairing of the two gods who bring the pleasant gifts of the earth and, significantly, are both overpowered by seasonal change. Just as the frost kills the fields and the vines, these two gods—unlike the Olympians—live in a world filled with regular suffering.
Hades, wanting a queen, kidnaps Demeter's only child, Persephone. Demeter wanders the earth in aimless despair, eventually resting in Eleusis in human disguise. One day, the kind family that has been harboring her accidentally discovers her divine nature and offends her. They build the great temple at Eleusis to appease her anger. Still, Demeter locks herself in the temple out of sadness, and at that time nothing grows on the earth. Finally, Zeus sends Hermes down to Hades to try to set everything right. Hades agrees to let Persephone return to her mother but slyly makes her eat a magic pomegranate seed that necessitates her return. Eventually a compromise is arranged: Persephone will stay with Hades for one-third of the year, Demeter for the other two-thirds. When Persephone returns to the underworld at the start of each winter, Demeter's renewed sorrow makes the Earth barren. Persephone returns each spring, causing Demeter's joy and thus the springtime's blossoming.
Dionysus is the only main god who has one human parent: Zeus is his father, but his mother is a mortal named Semele. Enraged at Zeus's affair, Hera cunningly fixed Semele's death while she was pregnant. Zeus snatched the baby from his mother's burning body and implanted it in his own side until birth, when Hermes carried the infant god off to be raised in secrecy by the nymphs of Nysa, a magic valley. Dionysus is generally a good god, spreading the secrets of wine production everywhere he goes. He even loves the mortal Ariadne after Theseus cruelly abandons her and dares defy Hades and rescue his mother from death. Somehow succeeding, Dionysus leads Semele up to live as an immortal in Olympus. He has another side, however; as one might expect from the lord of wine, he is a god of madness and insanity. The wild, bloody Maenads are his followers. When Pentheus, king of Thebes, defies him, Dionysus drives Pentheus's mother and sisters so insane that they rip Pentheus apart with their bare hands. Dionysus is the final component of the Greek pantheon, and as time goes on, his influence grows. He eventually becomes the god of holy inspiration, in whose honor the most famous theater and poetry festival is held. Taking place every spring, it commemorates his rebirth—according to one story, he is torn to pieces each year either by the Titans or by Hera's orders, depending on the version of the myth. Like Demeter's, his story is one of tragedy and death, though he always rises from the dead.
Hamilton introduces the Greek gods as divine beings whose actions offer some preliminary explanations for the mysteries of the world and also shows us just how much the gods resemble humans. They sometimes make mistakes, fight with one another, and in some cases even suffer. This human aspect of the gods cements the link between the divine and the visible world and lends credibility to the explanations the myths set forth, implying that the uncertainty and mystery of nature that surrounds us could be explained by the erratic actions of the gods. So, if it was puzzling to the Greeks that wine could cause drunken happiness and inspiration but also lead to wild, dangerous madness, its duality is reconciled by the stories that depict the dual nature of Dionysus himself. That deeply perplexing condition of the seasons—fields mysteriously lie barren for a third of the year and then break out into beautiful, flowery spring—is accounted for by Demeter's annual mourning for the loss of her daughter. Dionysus's duplicity and Demeter's depression are two very human qualities and allow us to explain otherworldly phenomena with reference to the same characteristics we see in other people in the visible world.
As these myths play such a vital role in explaining the innumerable twists and peculiarities of the world, it is no surprise that there is such an enormous cast of characters. The realm of waterways and navigation alone warrants a whole cast of characters in itself. Seafaring and sea trade were critically important to Greek civilization, so the Greeks felt a need to explain the complexities of bodies of water—hence the wide variety of water-oriented gods. The tumult of the seas and rivers can be explained by the warring wishes of their respective gods, just as a stormy sea could signify the anger of Poseidon and a calm sea the beneficence of a sea-nymph. Since much of what occurs in the waters is inexplicable, the Greeks could not ascribe it all to one all-powerful water god, therefore a whole host of divinities were used to explain the wide variety of watery mysteries. The large number of gods and beings thus indicates the complexity the Greeks found in the world around them, which is reflected in the intricate, specific explanations provided by their myths.
The complexity of the myths and the large cast of characters may also be due to the diversity of sources and traditions from which Hamilton compiles her material. She borrows from playwrights and poets whose works span two vastly different cultures and more than a millennium of history. Versions of the same myths differ across these sources, as Greek and Roman cultures had no singular work—like the Bible in Judeo-Christian tradition—to house a definitive version of their stories. Each author was thus an independent inventor, altering the myths to suit his own tastes and purposes. Hamilton herself is a similar kind of reteller, a redefiner and reinterpreter more than a simple collector of stories. She notes multiple versions of her stories, but usually prefers one over others. In any case, her retelling alerts us to the incredible depth of the world of Greek myth.