500
This is the reason that Jocasta didn't believe in prophesies.
She had a prophecy given to her which said that she would have a son who would kill her husband. To prevent it from coming true, she pinned her firstborn son's feet together, and left him on Mount Cithaeron to die. Because she believed her son to be dead, and her husband's death had nothing to do with her son, she thought that prophecies could be false, or at least avoided.