What are the two major themes of the play Oedipus Rex?

In
determining the themes of 's , it's important to understand the distinction
between a theme and a motif.

A
theme is a dominant central idea, message, or moral that the playwright
wishes to convey to the audience. A theme is often a universal truth, at least at the time the
play was written, and is often centered around society, human nature, or the human
condition.

A motif is a recurring idea, image, symbol,
or event that supports, reinforces, or helps to explain a theme.

It's also
important to understand the context in which the plays were written and performed. In Ancient
Greece, plays weren't intended for entertainmentthey were written and performed in order to
teach the audience a moral lesson.

Most of the plots of Greek tragedies were
based on ancient myths and legends that the audience grew up reading and hearing. The audience
already knew how the story was going to end when they went to see a play, so what was
interesting to the audience was not the myth or legend itself, but how the playwright dramatized
the myth and how the playwright dramatized the lessons to be learned from the myth.

A good question to ask is whether a particular idea or event is a
lesson or moral to be learned (a theme) or if the idea or event simply
supports the lesson to be learned (a motif).

A major theme in Rex is that the gods, not
individual human beings, determine an individual's fatethe idea of fate versus free
will.

No matter what Oedipus or anybody else does, no matter how much free
will Oedipus exercises (or thinks he does), he can't escape his fate. He
will kill his father and marry his mother because the gods said
so.

The Oracle is a major motif that supports the
theme of fate versus free will. The oracle made predictions based on the
will of the gods and provided guidance, often in cryptic terms. The oracle is discussed or
consulted several times during the play. Nothing having to do with consulting the oracle is a
theme of Oedipus Rex, but the oracle is a motif that
recurs throughout the play and which supports the theme of the will of the gods versus free
will.

Another major theme of Oedipus
Rex is that excessive pride () caused Oedipus' tragic downfall.
There's a lesson to be learned from the choices that Oedipus makes,
particularly the mistakes that he makes, based on his pride.

A
motif that supports this theme is blindness. In Oedipus
Rex, blindness symbolizes ignorance in the sense that somesimply don't know that
they're acting against their own or another character's best interest. Blindness also represents
a prideful refusal to see and acknowledge the truth of the prophecies, as well as a refusal to
recognize one's own faults.

In Oedipus Rex, Oedipus's
pride and his refusal to recognize the will of the gods lead to his tragic
downfall.