It is all about discoveries: Antigone discovers her punishment for trying to bury her brother's body: she will be buried alive. The unusual cruelty of such punishment is apparent to the reader. The sentry discovers Antigone's actions. Creon discovers the event himself and is enraged against Antigone. Ismene, Antigone's sister discovers that she no longer hates her late brother and that she also wants him to be properly buried.
The many discoveries force the audience to reflect upon the fact that there are hidden truths and realities behind someone's actions sincethey can compare Creon's view of civil laws and Antigone's view of Divine laws and understand that unless civil laws are moral, they are not to be obeyed.