What is Chance? What role does it play in Oedipus’ tragedy?

Really Sophocles is saying that the oracles and prophesiers have no power over our fate. Life is a series of chances that are both good and bad. Trying to dictate our own fate or force it is a futile endeavour,

"Fear? What should a man fear? Is all chance, chance rule's our lives. Not a man on earth can see a day ahead, groping through the dark."