Answer:
Creon said this at the end of the story when he realized that he was wrong and experienced catharsis.
Step-by-step explanation:
In the story 'Antigone', Creon decided to release Antigone from the prison and set up a tomb for Oedipus because the oracle Teiresias prophesied great suffering if Creon didn't undo his wrong doings.
After being convinced by Chorus and the prophecy foretold by Teiresias, Creon remarks the words "It is by the laws of heaven that man must live" at the end of the story to amend his misdeeds. He realized that it was wrong to take Antigone's life because it was against the laws of heaven.