from Apollo. Unfortunately, what he can see is usually bad news for the one who calls him in for advice, so it is common for the prophet not to be believed. (Who wants to believe gloom and doom about your fate and future, after all?)

In Oedipus Rex, Oedipus falsely accused Tiresias of being part of a plot with Creon to take over the country; in another great irony, Tiresias is now accused by Creon of having been bribed to tell untruths. Again, who wants to believe such painful and unflattering things. He tells Creon, just as he told Oedipus, that he was going to suffer because of his excessive pride:

All men make mistakes, but a good man yields when he knows his course is wrong, and repairs the evil. The only crime is pride.

Tiresias tells Creon that nature is rebelling against Creon for two reasons. First, Creon has angered the gods by refusing to allow his nephew to be properly buried. Second, he has angered the gods because he has put his young niece, Antigone, in a tomb for her disobedience. Creon stubbornly refuses to believe what he hears, and we are not surprised, as Creon has demonstrated his prideful stubbornness throughout this play.

The last thing Tiresias tells Creon before the prophet leaves is that Creon's family is going to be decimated because of Creon's sacrilegious behaviors. Creon does finally take some action to avert the disasters Tiresias predicted; however, he is too late and loses everyone who matters most to him. 

In Antigone, as well as in other Greek literature, Teiresias is a prophet, sent by the gods to reveal truth to those who will hear him.  Another name for a prophet is a "seer," and, ironically, this seer is literally blind though he is able to figuratively "see" the truth as well as the future.  That's what prohets do--they tell the truth and foretell the future--usually a future of doom and destruction.

In this story, Teiresias functions as an emissary of truth.  Oedipus the king has asked the Oracles to reveal the cause of his country's literal dying--children are stillborn, crops are withering, animals are dropping in the fields.  Teiresias arrives to, as requested, reveal the cause of the curse.  He speaks the truth, and Oedipus is named as the root and cause of the city's curse.  Instead of taking him seriously, as a representative of the gods who has come at his request, Oedipus does the same thing he did the last time he visited with an Oracle--he dismisses the idea as ridiculous and follows his own thinking and logic.  Even worse, in this case, he treats the old, blind prophet abominably.  Teiresias is scorned and mocked and even physically abused by the arrogant Oedipus.  The prophet's role is to speak the truth, to help the blind see, so to speak; instead, it is Oedipus who is blind and refuses to "see" the truth set before him.  Once his story has been made known, of course, Oedipus blinds himself, another twist of irony in this play.