Thetis

Pseudo-Apollodorus's Bibliotheke asserts that Thetis was courted by both Zeus and Poseidon, but she was married off to the mortal Peleus because of their fears about the prophecy by Themis^[4] (or Prometheus, or Calchas, according to others) that her son would become greater than his father. Thus, she is revealed as a figure of cosmic capacity, quite capable of unsettling the divine order.^[5]

When Hephaestus was thrown from Olympus, whether cast out by Hera for his lameness or evicted by Zeus for taking Hera's side, the Oceanid Eurynome and the Nereid Thetis caught him and allowed him to stay on the volcanic isle of Lemnos, while he labored for them as a smith, "working there in the hollow of the cave, and the stream of Okeanos around us went on forever with its foam and its murmur" (Iliad 18.369).

Thetis is not successful in her role protecting and nurturing a hero (the theme of kourotrophos), but her role in succoring deities is emphatically repeated by Homer. Diomedes recalls that when Dionysus was expelled by Lycurgus with the Olympians' aid, he took refuge in the Erythraean Sea with Thetis in a bed of seaweed (6.123ff). These accounts associate Thetis with "a divine past—uninvolved with human events—with a level of divine invulnerability extraordinary by Olympian standards. Where within the framework of the Iliad the ultimate recourse is to Zeus for protection, here the poem seems to point to an alternative structure of cosmic relations."^[6]

Once, Thetis and Medea argued in Thessaly over which was the most beautiful; they appointed the Cretan Idomeneus as the judge, who gave the victory to Thetis. In her anger, Medea called all Cretans liars, and cursed them to never say the truth.^[7]

Zeus had received a prophecy that Thetis's son would become greater than his father, as Zeus had dethroned his father to lead the succeeding pantheon. In order to ensure a mortal father for her eventual offspring, Zeus and his brother Poseidon made arrangements for her to marry a human, Peleus, son of Aeacus, but she refused him.

Proteus, an early sea-god, advised Peleus to find the sea nymph when she was asleep and bind her tightly to keep her from escaping by changing forms. She did shapeshift, becoming flame, water, a raging lioness, and a serpent.^[8] Peleus held fast. Subdued, she then consented to marry him. Thetis is the mother of Achilles by Peleus, who became king of the Myrmidons.

According to classical mythology, the wedding of Thetis and Peleus was celebrated on Mount Pelion, outside the cave of Chiron, and attended by the deities: there they celebrated the marriage with feasting. Apollo played the lyre and the Muses sang, Pindar claimed. At the wedding Chiron gave Peleus an ashen spear that had been polished by Athena and had a blade forged by Hephaestus. While the Olympian goddesses brought him gifts: from Aphrodite, a bowl with an embossed Eros, from Hera a chlamys while from Athena a flute. His father-in-law Nereus endowed him a basket of the salt called 'divine', which has an irresistible virtue for overeating, appetite and digestion, explaining the expression 'she poured the divine salt'. Zeus then bestowed the wings of Arce to the newly-wed couple which was later given by Thetis to her son, Achilles. Furthermore, the god of the sea, Poseidon gave Peleus the immortal horses, Balius and Xanthus.^[9]Eris, the goddess of discord, had not been invited, however, and in spite, she threw a golden apple into the midst of the goddesses that was to be awarded only "to the fairest." In most interpretations, the award was made during the Judgement of Paris and eventually occasioned the Trojan War.

As is recounted in the Argonautica, written by the Hellenistic poet Apollonius of Rhodes, Thetis, in an attempt to make her son Achilles immortal, would burn away his mortality in a fire at night and during the day, she would anoint the child with ambrosia. When Peleus caught her searing the baby, he let out a cry.

Thetis heard him, and catching up the child threw him screaming to the ground, and she like a breath of wind passed swiftly from the hall as a dream and leapt into the sea, exceeding angry, and thereafter returned never again.

Some myths relate that because she had been interrupted by Peleus, Thetis had not made her son physically invulnerable. His heel, which she was about to burn away when her husband stopped her, had not been protected. (A similar myth of immortalizing a child in fire is seen in the case of Demeter and the infant Demophoon). In a variant of the myth first recounted in the Achilleid, an unfinished epic written between 94 and 95 AD by the Roman poet Statius, Thetis tried to make Achilles invulnerable by dipping him in the River Styx (one of the five rivers that run through Hades, the realm of the dead). However, the heel by which she held him was not touched by the Styx's waters and failed to be protected.

Peleus gave the boy to Chiron to raise. Prophecy said that the son of Thetis would have either a long but dull life, or a glorious but brief one. When the Trojan War broke out, Thetis was anxious and concealed Achilles, disguised as a girl, at the court of Lycomedes, king of Scyros. Achilles was already famed for his speed and skill in battle. Calchas, a priest of Agamemnon, prophesied the need for the great soldier within their ranks. Odysseus was subsequently sent by Agamemnon to try to find Achilles. Scyros was relatively close to Achilles's home and Lycomedes was also a known friend of Thetis, so it was one of the first places that Odysseus looked. When Odysseus found that one of the girls at court was not a girl, he came up with a plan. Raising an alarm that they were under attack, Odysseus knew that the young Achilles would instinctively run for his weapons and armour, thereby revealing himself. Seeing that she could no longer prevent her son from realizing his destiny, Thetis then had Hephaestus make a shield and armor. According to the Hellenistic poet Phylarchus, Thetis once went to Hephaestus to ask him to forge weapons for her son Achilles, and he agreed on the condition that she would sleep with him. Thetis agreed, and when Hephaestus had completed the weapons she asked to put on the armor to make sure it would fit Achilles, for she was the same size as him. Now armed, Thetis fled Hephaestus' amorous advances, and because he could not run after her, he wounded her in the ankle with his hammer. Thetis was healed in a Thessalian town that was therefore called Thetidium, after her.^[10]

Thetis played a key part in the events of the Trojan War. Beyond the fact that the Judgement of Paris, which kicked off the war, occurred at her wedding to Peleus, Thetis consistently influenced the actions of the Twelve Olympians and her son, Achilles.

Nine years after the beginning of the Trojan War, Homer's Iliad starts with Agamemnon (king of Mycenae and the commander of the Achaeans) and Achilles (son of Thetis) arguing over Briseis, a woman married to Mynes (son of the king of Lyrnessus). She was kidnapped and enslaved by Achilles. After initially refusing, Achilles relents and gives Briseis to Agamemnon. However, Achilles feels disrespect for having to hand over Briseis and prays to Thetis, his mother, for restitution of his lost honor.^[11] She urges Achilles to wait until she speaks with Zeus to rejoin the fighting, and Achilles listens.^[12] When she finally speaks to Zeus, Thetis convinces him to do as she bids, and he seals his agreement with her by bowing his head, the strongest oath that he can make.^[13]

Following the death of Patroclus, who wore Achilles's armor in the fighting, Thetis comes to Achilles to console him in his grief. She vows to return to him with armor forged by Hephaestus, the blacksmith of the gods, and tells him not to arm himself for battle until he sees her coming back. While Thetis is gone, Achilles is visited by Iris, the messenger of the gods, sent by Hera, who tells him to rejoin the fighting. He refuses, however, citing his mother's words and his promise to her to wait for her return.^[14] Thetis, meanwhile, speaks with Hephaestus and begs him to make Achilles armor, which he does. First, he makes for Achilles a splendid shield, and having finished it, makes a breastplate, a helmet, and greaves.^[15] When Thetis goes back to Achilles to deliver his new armor, she finds him still upset over Patroclus. Achilles fears that while he is off fighting the Trojans, Patroclus's body will decay and rot. Thetis, however, reassures him and places ambrosia and nectar in Patroclus's nose in order to protect his body against decay.^[16]

After Achilles uses his new armor to defeat Hector in battle, he keeps Hector's body to mutilate and humiliate. However, after nine days, the gods call Thetis to Olympus and tell her that she must go to Achilles and pass him a message, that the gods are angry that Hector's body has not been returned. She does as she is bid, and convinces Achilles to return the body for ransom, thus avoiding the wrath of the gods.^[17]

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  Head of Thetis from an Attic red-figure pelike, c. 510–500 BC, Louvre.
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  Thetis on an antique fresco in Pompeii, 1st century