Greek Myths were used as ways to explain how everything came into existence, but they were also stories that were told for enjoyment. In order to make many of these tales entertaining the ancient Greeks used the idea of the dominance of fate: this was when a character would attempt to avoid their prophecies, but this venture to circumvent fate only made the prophecy more likely to occur. The dominance of fate was such an important part of ancient Greek entertainment it occurred in several stories from the birth of the gods to the downfall of the city of Troy. The irony of characters causing their own demise was enjoyed among ancient Greeks.
This idea of the dominance of fate was justified in Greek myth by the Moerae. The Moerae were the sisters of fate Clotho, Lachesis and Atropos they were in control of spinning, measuring and cutting(respectively) everyone's thread of destiny: which essentially was their fate. The Greeks believed that no one was exempt from the Moerae's ruling, not even the king of the gods, Zeus. The Moerae could be considered the most powerful beings in the world because of this ability. Ancient Greeks told stories about self-fulfilled prophecies and the idea that fate is all-powerful in order to entertain the audience to emphasize the true reasons for the myth.
The first victim of the dominance of fate is the Titan king, Cronus. When Cronus defeated his father, Uranus, he was told by Uranus that his children would be his demise. In the Bibliotheca, in order to avoid his father's foretelling, it is said that Cronus "he used to swallow his offspring at birth. His firstborn Hestia he swallowed, then Demeter and Hera, and after them Pluto and Poseidon. Enraged at this, Rhea repaired to Crete, when she was big with Zeus and brought him forth in a cave of Dicte." (Apollodorus, The Library 1.1.5-1.1.6) When Zeus grew up he defeated his father and saved his siblings fulfilling his grandfather's prophecy. Scared of his prophecy Cronus pushed rhea to save Zeus. This fear that made Cronus eat his children also angered Zeus and caused Zeus to dethrone his father. The irony of this self-fulfilled prophecy is used as a tool to enhance the importance of the rise of the king of Olympus.
Another character in Greek myth who fell to the dominance of fate in the form patricide would be Laius, father of Oedipus. Laius was the king of Thebes. Learning from an oracle that his son would kill him, Laius ordered a shepherd to leave his son on Mount Cithaeron to die. The shepherd felt bad for the child and gave Oedipus to Polybus, the king of Corinth. When Oedipus grew up he left Corinth in order to escape one of his own prophecies. On the road a chariot ran over his foot, enraged Oedipus killed the man in the chariot who turned out to be Oedipus's birth father.
While Oedipus enforced dominance of fate in the previous story he also fell to it at the same time. When Oedipus was in Corinth he was curious to find his birth parents. Oedipus visited the oracle in Delphi to solve the mystery of his birth. The Oracle did not reveal his birth parents but rather prophesized that Oedipus would kill his father and marry his mother. Terrified of such a horrific affair he left Corinth, killed his father on the road and arrived at the city of his birth. Thebes was under attack by the Sphinx and with no king to sit on the throne Laius's brother-in-law, Creon, declared that whoever could defeat the monster would receive the throne as well as Creon's recently widowed sister. When Oedipus defeated the Sphinx he was awarded his mother as a wife, fulfilling the prophecy of the oracle. In Homers Odyssey, Odysseus when talking about Oedipus's mother, says "Oedipus" mother I saw, Epicastê, famous in story. she, all unknowing, committed a great and terrible crime, marriage to her own son. Unknowing, he murdered his father, then married Episcastê. The gods set the pair as a warning."(Homer, Odyssey 11.1271-1274) Ancient Greek writers used the irony of self-fulfilling prophecy as a way to warn people of the wrong doings of Oedipus and Episcastê.
Self-fulfilling Prophecies tend to be common among Greek myths with the dominance of fate. But there are still other incidents where characters don't directly or indirectly cause their own demise, but despite their best efforts to avoid fate, their expiration is still imminent. For example, King Aeëtes, the king of Colchis, was told by an oracle that when the golden fleece is removed from the city of Colchis then Aeëtes would lose the throne. In order to avoid this Aeëtes closed off Colchis from the rest of the world and fought off all intruders. When the Argonauts came to Colchis Aeetes allowed them in knowing that they were stronger than his army. Instead of fighting Aeëtes told Jason to complete what he thought was an impossible task. When Jason completed the task with the help of Aeëtes's daughter, Medea, Aeëtes decided to attack the Argonauts. before Aeëtes could strike, medea in an act of betrayal, gave the golden fleece to Jason and assisted the Argonauts in their escape. Despite Aeëtes's best efforts to retain the fleece and his kingship, he lost all of it.
The power of fate was not only limited to individuals it also foretold the fall of Troy. Hecuba, Queen of Troy, while pregnant with Paris dreamt of giving birth to a torch covered in snakes. With the guidance of prophets, she realized that her next child would cause the fall of Troy. To save her city Hecuba commanded her servants to kill her newborn son, Paris. Unable to bring themselves to commit infanticide they left Paris alone on a mountain. A shepherd found and cared for the child until Paris returned to troy. After Paris judged that Aphrodite was more attractive then Hera and Artemis, Aphrodite awarded him with the love of the most beautiful women, Helen. Menelaüs was already married to Helen, but Paris took Helen and escaped to troy. This act of adultery caused the Trojan war which led to the end of Troy.
One of the most distinguished figures who lost to fate was Acrisius, the king of Argos. When Acrisius daughter, Danaë, was born an oracle foretold that Danaë's son would kill Acrisius. to avoid this Acrisius locked Danaë in an underground chamber. Zeus came to her in the form of a golden shower and impregnated her to Acrisius's discontent. When Danaë gave birth to Perseus Acrisius decided to improve their prison by locking them in a box and releasing it to the sea. The anxious king's plan failed again; a Fisherman, Dictys, rescues Danaë and Perseus when their prison was caught in the fisherman's net. Many years later, Perseus traveled to Argos to visit his grandfather, but Acrisius decided to run from his foretold murderer. In the Myths of Hyginus, Hyginus says "wind blew a discus from Perseus' hand at Acrisius' head which killed him. Thus what he did not do of his own will was accomplished by the gods".(Hyginus, Fabulae 63) In spite of all the precautions Acrisius took to ensure his safety, Perseus killed him by accident because of divine intervention. Even though it wasn't Acrisius fault for his own death, the gods enforced the dominance of fate.
The dominance of fate and self-fulfilled prophecies were such an entertaining part of Greek mythology that these motifs outlived ancient Greek culture. Shakespeare used the idea of a self-fulfilled prophecy in "The Tragedy of Macbeth". Even in modern media self-fulfilled prophecies are used as entertainment. For example, in the Disney channel show "That so Raven" the protagonist, Raven, is able to see glimpses of the future, but in order to protect herself from the incident, she saw she causes it to occur. Due to the irony and humor of these types of story, ancient Greeks were able to understand the story of everything that happened before their time.