Compared with his brother Zeus, Poseidon (Poseidaon, Doric Poteidan) is a simpler figure, less popular, less universally worshipped, and much less capable of development into a grand and enlightened theological concept. Perhaps the most likely etymology of his name is Kretschmer’s, ‘husband of Da’, Da being plausibly thought to be an old, probably pre-Greek, name the goddess whom the Greeks called Gaia (Attic Ge) in their own language. This agrees with Poseidon’s common title Gaiochos, ‘Holder, Embracer (i.e., husband) of Earth’ If he is a primordially Greek god, his original realm cannot have been the sea, for the Greek invaders came from somewhere inland; when they reached the Mediterranean Basin and took to navigation, their god too became marine.
It is not at all certain that he was originally conceived as of human form; several legends and his standing title Hippios, ‘He of the Horse(s)’, are consistent with his having horse-shape. That he was always connected with water is, however, very likely; water fertilizes the earth, and earthquakes, which he governs, may have been thought due to water undermining the ground. For a land-bound people economically dependent—as the Greeks always were—on animal-husbandry, the fact that livestock must daily drink at some watering-hole or die would have indued any god of waters with immense importance, so that Poseidon might well have been an aquatic deity long before the people who recognized him ever saw salt-water.
However, his most prominent function as we actually know him from historical Greek culture in the eastern Mediterranean is that of sea-god, and it is in this capacity that we find him, in Homer, wrecking Odysseus, who had earned his hatred, and again and again rising from, plunging into, or journeying over the sea, which was given him when the three sons of Kronos cast lots for the universe. The Romans, for want of a better equivalent (for they had originally no maritime gods whatsoever), equated him with a rather obscure water-deity Neptunus, anglicized into Neptune. In art, he is shown as a tall and stately figure, not unlike Zeus in general appearance, but distinguished by his attribute, the trident, and sometimes by his wilder and more uncouth appearance, a feature exaggerated in Hellenistic art especially.
Poseidon’s consort is the not very important Amphitrite. This goddess is worshipped here and there, along with the Nereids, of whom she is generally reckoned as one, although one lyric passage of doubtful date calls her their mother, apparently through a blending of Poseidon with Nereus. She was an unwilling bride, according to one story at least, for she was carried off by Poseidon, or at any rate ran away from his advances and took refuge with Atlas, or with Okeanos, until at last the dolphin found her, in gratitude for which Poseidon turned him into the constellation of that name. Once married, she was a jealous wife, and not without cause. Poseidon paid court to Skylla, daughter of Phorkys and Hekate or Kratais. Amphitrite heard of it, and put magic herbs into her rival’s bathing-place. The effect was to turn her from the loins down into a horrible monster, encircled with a ring of dogs’ heads, who thenceforth became a terror to all mariners, seizing on and devouring them as they sailed past her cave (traditionally located in the Straits of Messina; rationalizers of various dates are at pains to explain away this picturesque sailors’ yarn by assuming a whirlpool, rock, or other natural danger).
Concerning he children of Amphitrite, read the file about Triton.
In considering Poseidon’s mythical nature, we have to remember that he owes something to foreign sea deities, whose influence has been traced in later times (for example, the Mylasian Zenoposeidon, i.e., Zeus-Poseidon, who developed out of the Karian god Osogos), and may reasonably be guessed at for earlier periods. What specific characteristics Poseidon inherited from such earlier, pre-Hellenic gods is not known, but we do know that the Greeks came by land to the country they occupied in historical times, and brought with them no sea-mythology, whatever they may have found there. Their historically attested Poseidon is nearly always shown (unlike Nereus) as violent, rough, and ill-tempered, whether by sea or on land; a sea-god pure and simple would surely be sometimes calm. No very sharp line can be drawn between Poseidon and such figures as Briareos, who indeed was sometimes represented as either the son or the son-in-law of Poseidon.
The early stages of Poseidon’s development are difficult to trace, for in Homer we already meet him as a fully-formed god, completely anthropomorphic, whose nature is assumed by the poet to be known to everyone. He is a violent partisan, who from first to last does everything possible to help the Achaians and harm the Trojans. For this he has an intelligible reason enough; Laomedon, father of Priam, had employed him and Apollo to build the walls of Troy, and when they had finished their task, refused to pay them. It is curious that Apollo, who throughout the Iliad is the constant friend of Troy and in particular of Hektor, is associated with Poseidon in this matter; in fact, Poseidon himself remarks upon it. Poseidon, then, is consistent in his hatred and desire for revenge; the reason for his servitude to a mortal was the rebellion against Zeus.
There is an interesting variant of the tale in Pindar; the task of building Ilion’s wall was shared by a mortal, the hero Aiakos, and as his work was less strong than that of the gods, it was his part of the wall through which the Greeks finally broke. In the Odyssey, Poseidon’s enmity to the hero is one of the chief motifs of the whole story. Odysseus had blinded the Kyklops Polyphemos, Poseidon’s son by the nymph Thoosa, daughter of Phorkys. In both poems he is a savagely majestic figure, represented as of enormous strength, even for a god, and prodigious speed; when he descends to battle with the other gods, Hades fears that he will split the earth above his head, and four strides take him across the sea from Samothrace to Aigai, where his palace is. His standing epithet is Earth-shaker (ennosigaios, enosichthon), and a stroke of his trident is enough to shatter a rock and drown the man standing on it; a mere trifle to some of his recorded feats of destruction.
Violent in all things, Poseidon was a violent lover, although stories of this kind are less common in his case than in that of Zeus. This is very natural; the traditional epithet of his element is ‘unharvested’ (atrugetos), i.e., barren, and his activities as god of fresh water are not very prominent. Hence there is no special reason for exhibiting him as lover or husband. His connexion with Medusa is mentioned in the file about the Gorgones, q.v.; he is also represented as either the father or the lover of the Harpies, or one of them. More important, and illustrating another side of his activities, is his connexion with Demeter Erinys (‘Raging’). The legend, as told at Thelpusa in Arkadia, was as follows. While Demeter was searching for her lost daughter, Poseidon saw and loved her. To avoid him, she took the form of a mare, but he assumed the shape of a stallion, and so forced his attentions upon her. From this union was born the wonderful (flying) horse Areion or Arion, also a daughter, whose name only the initiated might know.
Practically the same legend was told at Phigaleia, where Demeter was represented as black and horse-headed, but here the child of the union was the goddess Despoina (‘The Mistress’, one of the names for the queen of the under-world). No good explanation has been found as to why the anger of the goddess should be so strongly insisted upon, not only in the legend, where it might be thought no more than a picturesque detail, but also in her cult-title. That the offspring of the union should be the horse Arion in one case, Persephone or a goddess equatable with her in another, need not be part of the original story; Arion is famous in epic as the horse of Adrastos, whose story is given in the file about the Theban king Eteokles, q.v.; in another legend, preserved only in a scholiast on Homer, Areion is the offspring of a Harpy and Poseidon.
A very considerable number of heroes are credited with being sons of Poseidon; his children in general were, like their father, of ungentle character. Indeed, his reputation as a begetter of strong but rough men lasted quite late; Sextus Pompeius, for example, gave out that he was the son of Neptunus, who of course had been fully identified with Poseidon long before that time. Among Poseidon’s consorts, the most noteworthy is Ge herself (see above), and his association with ‘Demeter’ points the same way, for her name is plausibly explained as ‘Mother Da’. Although he and Earth are sometimes enemies (he fights against her sons, the Giants), it is understandable that a god whose domain includes fresh water should now and then be thought of as fertilizing the Earth; indeed, one of his cult-titles is Phytalmios, or nurturer-of-plants. The son of this union was the giant Antaios, with whom Herakles wrestled. This monster was unconquerable by any ordinary wrestler, or even by one of his own prodigious strength, for every time he was thrown he arose stronger than ever, from contact with his mother. Herakles, however, perceived this, and so heaved him in the air and managed to crush him to death with his hands. At least, so the story is commonly told; but writers up to and including Diodoros of Sicily describe the contest as simply one of wrestling, with the loser’s life for the stake, and those representations in art which show the hero lifting his antagonist in the air are not very early.
Poseidon is credited with some minor love affairs with beings known or plausibly supposed to be goddesses. They are as follows. By Alkyone or Halkyone, one of the Pleiads, he became the father of several persons of heroic rank, mostly connectecd with the sea in one way or another, namely Hyrieus or Urieus, founder of Hyria or Uria on the coast of Boiotia; Aithusa, important only for having had by Apollo a son Eleuther, founder of the town Eleutherai; Hyperenor, Hyperes and Anthas, of whom the last two also founded sea-coast towns. By a sister of Alkyone, Kelaino, he had three more children Nykteus, Lykos, and Eurypylos. There is nothing remarkable in the sea-god being thus represented as husband or lover of those stars whose rising and setting marked important dates in the Greek seaman’s calendar. Another not inappropriate bride of the god was Chione, i.e., Snow-girl, daughter of Boreas and Oreithyia, who threw her child Eumolpos into the sea when he was born, to hide her shame. Poseidon however rescued him. She may conceivably be a spirit of snowstorms.
The best-known tale concerning Poseidon is a local Attic legend describing how Poseidon and Athena strove for the land of Attica, and the gods, or the king, or the people judged between them. Poseidon wrought a miracle: with a blow of his trident he produced a salt spring from the rock of the Akropolis; the marks of his blow are to be seen to this day, underneath the porch of the Erechtheion, with an opening left in floor and roof above them, that they may always lie open to the sky. According to another account, he produced a horse, the first ever seen. But Athena planted, or magically evoked with a touch of her spear, an olive-tree, and the divine or human judges pronounced her victor. Poseidon in great wrath flooded the Thriasian Plain. At last the gods brought about a reconciliation, and henceforth Poseidon was much honoured in Athens, and especially was worshipped as Poseidon Erechtheus, a title behind which there certainly lies some early connexion between him and the mythical king Erechtheus, but the question of exactly what that connection may be is complicated and obscure. The salt spring was still shown to visitors in the days of Hadrian, together with the sacred olive, which was said to have grown again, two cubits in a day, after the Persians burned it.
This is the most familiar legend of its kind, but there are others. At Argos stood a temple of Poseidon Proklystios (the Flooder), concerning which the local legend ran as follows: Poseidon and Hera strove for the Argolid, and Inachos and his fellow-judges decided in favour of the great native goddess. Poseidon then flooded the country, but Hera appeased him, and when the waters retired his temple was built. At Trozen again, he strove with Athena for possession of the land, until Zeus adjudged that both should hold it, the god under the title of Basileus (Lord), the goddess as Sthenias (the Mighty) and Polias (Queen of the City). Whether for this cause or some other, he flooded the land and made it unfruitful with his salt waters, until he yielded to the sacrifices and prayers of the people, who thenceforth worshipped him also as Phytalmios.
Another series of legends tells how he created the first horse, or at least first introduced the art of taming horses. The tale of Areion or Arion has already been told; the other horses of the other local legends were, like him, marvellous creatures, winged and gifted with the power of speech. One of these miracles was located at Petra in Thessaly. Poseidon, there worshipped as Petraios (He of the Rock), was said, while asleep, to have fertilized the rocky ground, from which sprang the horse. Elsewhere, he is said to have struck the rock with his trident to produce it. Poseidon also sends or creates bulls, a frequent embodiment of the powers of water, whereof the legends of Pasiphae and of Hippolytos furnish examples.
Finally, Poseidon in his capacity as an earthquake-god is credited with the authorship of some striking natural formations, notably the pass of the Peneios, the natural drain which carries off the waters of the plain of Thessaly.