Homer's epic poems the Iliad and the Odyssey are our earliest surviving Greek literature, and our earliest sources for the Greek myths. Let's look at just two aspects of what this means.
First, Homer gives one version of the myth, but we very commonly find different versions elsewhere – there is no single, canonical version of any Greek myth.
Second, when Homer gives at any length a myth from outside his main storyline, he gives it paradigmatically. That is to say, the myth is not given as simply a piece of story-telling, but it is told by one of Homer's speakers in such a way as to make a point, to direct his listeners to some present course of action.
An obvious example is the story, referred to repeatedly in the Odyssey, of how Agamemnon, the Greek commander-in-chief in the Trojan War, returned home after the War and was immediately murdered by his wife Clytemnestra and her paramour Aegisthus, and how in due course Agamemnon's murder was avenged by his son Orestes. Odysseus, too, is on his way home from Troy and he is repeatedly warned:
"Do be careful when you get home. Remember what happened to Agamemnon …".
At home Odysseus' son Telemachus is - somewhat slowly - growing up, and he is enjoined:
"Do be worthy of your father. Remember how Orestes …"
Now to Oedipus in Homer. His single appearance in the Odyssey is in Book 11, where Odysseus visits the Underworld, and there meets, among others, the spirit of the departed Epikaste, the mother of Oedipus. Epikaste tells him how, "in ignorance", she married her son, shortly after Oedipus had killed his father. The gods soon made this known, whereupon, while Oedipus continued to rule at Thebes, Epikaste hanged herself.
In the Iliad there is a single, glancing reference to Oedipus in Book 23, which only confirms the Odyssey version of Oedipus continuing to rule after the gods' revelation.
Oedipus' name is now a household word; and these scanty appearances in Homer cannot have had anything to do with that. Far and away the best known version of the myth - the version from which, for instance, the founding fathers of psychoanalysis and structuralism, Freud and Lévi-Strauss repectively, drew their seminal studies - is that of Sophocles, in his play Oedipus Tyrannus, or Oedipus the King. Some 250 years or so separate Sophocles from Homer; and while Sophocles has the mother named Jocasta rather than Epikaste, he agrees with Homer that she married her son, and hanged herself when the truth came out; also that Oedipus prior to this marriage had murdered his father. But there is very little, if anything, else on which they agree.
Let's look now at a significant difference between the two versions of the story; an aspect which is important in Sophocles and is simply not in Homer at all. This shows not simply the non-canonical nature of the myths; but also how Sophocles is following a procedure which is very similar to Homer's paradigmatic use of myth.
In Homer the myth from the past is told in order to shed light on the present situation; Sophocles presents a version which tells a story from the past, but does so in such a way that it raises and reflects issues of contemporary concern, issues that are within the day-to-day experience of his audience.
Firstly, there's the role of oracles. Oracles do not feature in Homer, but in Sophocles they play a very important part. It is on instruction from the oracle at Delphi that Oedipus embarks on his search for the murderer of his predecessor as king of Thebes, Laius. And when this search leads to the revelation that the murderer was none other than himself, this leads to the further revelation that a much earlier oracle, one which had foreseen that Oedipus would murder his father and marry his mother, was true – Oedipus is the son of Laius, and the son, as well as the husband, of Jocasta.
There are occasions when the reliability of this earlier oracle is called into question. Jocasta exclaims (at lines 857-8 of the play),
"So much for prophecy. From now on I'll pay no regard to it at all".
And again (977-9),
"No reason at all to fear the future. It's Chance that rules our lives, there is no certain foreknowledge of anything. Far better for us to live at random, just doing as well as we can."
Such pronouncements are horrifying to the Chorus of reverent Theban elders and they declare (895-903) that if oracles are not to prove infallible, then they will no longer need to serve the gods with their dances, and will no longer journey to the holy seats at Delphi and elsewhere. But the play does of course ultimately show that these misgivings have been unfounded – the oracles were right all along.
There is ample evidence of a gathering mistrust of oracles, and of the validity of traditional religion, in Sophocles' day. One of our best sources is the contemporary historian Thucydides who, in relating the effects of the deadly plague that struck Athens in 430 and again the following year, says (2.53) that it created a state of "unparalleled lawlessness", in which, "Men were not held back by any fear of god or law", but, "as far as the gods were concerned, it seemed to make no difference whether one worshipped them or not".
"Only from Death can Man not find any rescue. Even from plague he has devised escape."
Another factor was the growing confidence, in some quarters, in the achievements of man, and a consequent feeling that there was little, if anything, that man could not achieve on his own, without help from the gods. What need, or even what grounds, were there for belief, or trust, in the gods? Do the gods even exist? Sophocles himself, in a choral ode from an earlier play, Antigone, had celebrated the spectacular achievements of man in such matters as navigation and agriculture. "Only from Death can Man not find any rescue. Even from plague he has devised escape." And the philosopher Protagoras pronounced, "Man is the measure of all things", and, "About the gods I am unable to discover whether they exist or not".
This leads me to the second difference between Homer and Sophocles that I wish to consider, namely the question of who brought Oedipus' incestuous marriage to light. Epikaste is explicit that it was the gods. But in Sophocles, the moment Oedipus hears from the oracle that the murderer of Laius must be found, he springs into action himself, and single-handedly uncovers that he is himself the murderer, and also the son of Jocasta. Oedipus is behaving like Protagoran man – as though he were the measure of all things.
But the result of his self-imposed search is the discovery that he is not the man he thought he was – not the all-competent, all-powerful ruler of his city, but instead a man guilty of parricide and incest, and only worthy to renounce his city and his family and go into exile. (His going into exile is another flat contradiction of Homer.)
The choral ode from Antigone, after three verses celebrating man's great achievements, concludes in its final verse that for all these achievements, man will not get anywhere unless he shows proper respect for the laws of the city and the gods. In