It is the job of the Greek Chorus to both participate in the events of the play and comment on these events. In Antigone, the Chorus is of Theban Elders, which suggests that they are the ones who hold the tradition and memories of the past events that affect the story of the play.
This play continues a story that began in Oedipus Rex. Oedipus, Antigone's father, tried to defy the oracle of the gods and escape his fate. It was ordained that he would kill his father and marry his mother. In trying to outwit this prediction, he actually ran right into the events that sealed his fate. The lesson of the story of Oedipus was that no human can outrun or outwit the will of the gods.
The story of Oedipus is important here, since this is what, in summary, the Chorus is reiterating in Ode 3, which begins at line 596. The Elders are warning the audience that they must not forget the lessons of the past. That, if their personal family history is free of being "shaken by the gods," they are blessed and will not have to continue to pay the price through generations, as Antigone must pay the price for Oedipus' sin.
They end with a warning:
For indeed wide-ranging hope
is a blessing to many men,(625)
but to many also a trick of light-minded desires.
It comes to one who knows nothing
until he burns his foot
walking in hot fire.
Hence the old saying still shows its wisdom:(630)
Sometimes the bad seems good
to one whose wits
God leads to madness.
He will last a short time without ruin.
By suggesting that "[s]ometimes the bad seems good," the Chorus is cautioning the audience from following in Antigone's footsteps and ignoring the lessons of the past.