The use of lightness or brightness is supposed to invoke a sense of happiness or safety. "His face is bright. [ . . .] his news too may be bright for us and bring us safety" (79-81). In this, the reader gets a sense that Apollo is happy, and his news will hopefully be as cheerful.
The use of light is also symbolic of seeing or vision. Oedipus says, "Your life is one long night so that you cannot hurt me or any other who sees the light" (374). In this, the words "one long night" symbolize the darkness that Teiresias must see because of his blindness. " . . . who sees the light" is referring to those who can see. Darkness is used in the story for not only a sense of the blindness, but also a sense of evil or unhappiness. "When the dark singer, the sphinx . . ." (392) helps the reader understand how the characters feel about the sphinx. They refer to the sphinx as evil and dark.
In about line 418, the phrase "darkness on your eyes" is foreshadowing of what will become of Oedipus. This metaphor for blindness, which one saw earlier, makes the reader think about what will become of Oedipus. Later, when Oedipus stabs himself in the eyes with his mother's broach, he will experience the same "darkness" as Teiresias.
Sophocles's use of light and dark in Oedipus the King had many different meanings. Light shows good and happiness while dark shows meanness and evil. Light becomes a metaphor for vision. If one can see, all is bright and light. Dark is the metaphor for blindness. If one cannot see, everything is dark and like the night. Sophocles uses these metaphors to add color to the