Neptune did, however, make an appearance in the opening book of Virgil's Aeneid. Juno (Hera to the Greeks) had, with the help of Eurus, sent a huge storm towards the Trojan fleet. Poseidon heard the commotion from his underwater palace and surfaced to see what the cause of it was. He became furious at Juno and the winds for overstepping into his domain and yelled to the winds, "Is it for you to ravage seas and land, unauthorized by my supreme command?… Hence! to your lord my royal mandate bear - The realms of ocean and the fields of air are mine, not his. By fatal lot to me the liquid empire fell, and trident of the sea" (5). He makes it very clear here that he is the ruler over the ocean realm and that he does not want anyone or anything infringing upon his reign. In doing so, Neptune reaffirms his association with jealousy and anger that Poseidon possessed throughout Greek myth and confirms that the legacy of Poseidon would continue among the Romans.
Poseidon's influence would be felt long after the days of the Greek heroes. Roman mythology included Neptune, a god virtually equal to Poseidon in both relations and attributes. But, he did not play as large of a role in Roman mythology as Poseidon did in Greek, probably a result of the Romans being much more land-oriented than the sea-faring Greeks.
Poseidon and Athena are often found at odds with each other, like they were in the Odyssey. The city of Athens was the site of one such confrontation. Both gods wanted the city to be a site for worship to themselves and wanted it to be named after them. As gifts to the Athenian people, Poseidon struck the acropolis with his trident, forming the Erechtheis Sea, and Athena planted the first olive tree. "When the two strove for possession of the country, Zeus parted them and appointed arbiters… And in accordance with their verdict the country was adjudged to Athena because… she had been the first to plant the olive. Athena, therefore, called the city Athens after herself" (Apollodorus 2, 79-81). The arbiters were a group composed of gods and goddesses. All of the gods voted in favor of Poseidon and all of the goddesses voted in favor of Athena. Because Zeus abstained from the vote, there was one more goddess than there were gods and Athena won possession of the city.
The battle with Athena over Athens was not the only one Poseidon would take part in on behalf of claiming a city for himself. He also tried claiming Troezen from Athena, which became shared equally between them. He received only the Isthmus of Corinth when he vied with Hêlios for control of it. Resulting from this conflict, the Isthmian Games were created in Poseidon's honor and featured horse and chariot racing, sports that he was associated with (). Poseidon was entirely unsuccessful in trying to take control of Aegina from Zeus, Naxos from Dionysus, and the Argolis from Hera (). All of these confrontations were brought about by his jealous nature.
Being a major Greek god, Poseidon also appeared many places in Greek literature outside of Homer's works. Because Homer's Iliad and Odyssey focus on Achilles and Odysseus, rather than on the gods, much of what we know about the gods comes from other sources. Among others, Apollodorus, Hesiod, and Pausanias wrote much of what we know about Poseidon today.
On one occasion, Poseidon found the resourceful Odysseus on a raft within sight of land. The sea and the wind rose at Poseidon’s command and with his trident, he staggered the sea and let loose the storm blasts against Odysseus and his tiny raft. Before the raft was smashed to splinters, a sea goddess, , saw Odysseus and gave him her veil as protection from drowning but Odysseus was afraid that this was just another one of Poseidon’s tricks. He waited until the raft sank below the crashing waves before he accepted the goddesses help and began the three day swim to the foreign shore. Satisfied that harm but no death had befallen our cursed hero, Poseidon turned away from the long-suffering Odysseus and made his way to his palace.
Polyphemos was a Cyclops, one of the ‘wheel-eyed’ giants who assisted at his forge. Polyphemos was the son of Poseidon and the sea nymph . When Odysseus came to Polyphemos’ cave, he and his shipmates were shocked to find that Polyphemos was a man eater. Polyphemos thought he had the puny sailors trapped so he let his guard down. Odysseus relaxed Polyphemos with some potent wine and clever talk, then sprang upon the Cyclops with a burning spear. The monster was blinded as his eye was boiled in the socket. Odysseus made his escape but, in his pride, he turned and taunted Polyphemos with cruel insults. Poseidon would not forgive the indignity that Odysseus had visited upon his son and Zeus could not save Odysseus from Poseidon’s wrath. Poseidon caused Odysseus and his family constant misery but he did not kill the haggard wanderer, he just kept driving him away from his home and thus, his happiness.
After releasing his brothers, Zeus led a war against Cronus and the other Titans. The war had waged for ten years when Cronus' three sons released the Cyclopes from captivity on advice of a prophecy from Mother Earth. In gratitude, the Cyclopes gave each of the brothers a weapon. Poseidon received a trident, Zeus a thunderbolt, and Hades a helmet of darkness. They used these gifts to finally defeat Cronus and the rest of the titans. Now that the three brothers were the rulers of all existence they decided to draw lots to determine their domains. Poseidon drew water, Zeus drew the sky, and Hades drew the underworld. The Titan Oceanus then resigned his rule over the watery realm to Poseidon (Guerber 126). There were other gods associated water, such as the personified river gods, but they were under the control of Poseidon. Being the ruler of the seas, Poseidon built a palace for himself underwater near Aegea in Euboea. He generally resided there, even though he was officially one of the Olympian Gods ().
Poseidon is not merely the god of the sea, but it also known as the Earth-Shaker and god of the Sable Locks. In art, he is generally represented as a mature, bearded man and is associated with horses, dolphins, and his trident. Like many of the Greek gods, he represents a set of standards that is somewhat ambiguous. More than anything else, he represents a changing character. His attitudes, like water, are constantly shifting. Poseidon is benevolent and helpful to mankind at times, but can quickly become jealous, angry, and destructive. Poseidon's swaying character often embodies the same traits that the water he rules over displays. Harold Bloom applies this idea to the struggle between Athena and Poseidon throughout the Odyssey and states, "We might trace then a politics pitting the forces of the land and civilization against the forces of the sea and brute mindlessness" (137). The brute force of the sea is applied to both Poseidon and his relations in both Homer's poetry and other pieces of Greek literature.
Poseidon's emergence as a god took place in about 2,000 B.C. among the Ionians and Minyans in Greece. He was the most dominant and powerful god for these people and possessed the control of thunder and earthquakes. Poseidon's thunder could be so powerful that it was often associated with the pounding of horses' hooves (). His association with earthquakes gave him the name of Earth Shaker, which, to the Greeks, was synonymous with his real name. Although he was often referred to as Earth Shaker in later Greek works, he is rarely seen actually causing earthquakes. Poseidon's reign as the dominant god of the Greeks ended sometime around 1450 B.C. when the Achaeans entered Greek territory and brought their god, Zeus, with them. The mingling of the two societies led to an intertwining of their religious beliefs and resulted in Poseidon becoming known as Zeus' brother.
The rewards and punishments that Poseidon, and the other Olympians, visit on their friends and enemies are as fair or harsh as Zeus will permit. As an example: blinded Poseidon’s son and received an epic punishment. Actually, if Odysseus had simply blinded he might have been forgiven, but Odysseus went too far, he added insult to injury. He, and his family, paid dearly for his transgression.