Octavius has introduced Octavia to Antony, and Antony tells her that although his business will take him from her side, he will be faithful to her and will behave “by th’ rule,” even though he has a reputation for behaving wildly. Octavia and Octavius leave, and a soothsayer enters. The soothsayer tells Antony to return to Egypt.
It is unclear to what degree Antony’s promise is a genuine one. He is either being deceptive to Octavia, or to Cleopatra, whom he assured of his enduring love. The soothsayer gives Antony a warning that, given how the historical events actually played out, is a wise one.
Antony asks him whether his or Octavius’ fortune will be better, and the soothsayer says Octavius’ will be. He warns Antony not to stay with Octavius, and says, “If thou dost play with him at any game, / Thou art sure to lose.” Antony sends the soothsayer away and then sends his man Ventidius to Parthia. He says that he thinks the soothsayer is right, and plans to return to Egypt. He says that he is marrying Octavia for peace, though “I’ th’ East my pleasure lies.”
Antony tries to predict the future. In an example of dramatic irony, the audience or reader knows how Antony’s future will turn out—just as the soothsayer warns him it will. Antony regards his marriage to Octavia purely as a strategic necessity, suggesting that his promise to her just before was a strategic lie.