Dumas' The Count of Monte Cristo is not a book filled with many metaphors. The reader discovers the theme of the story as Dantes realizes for himself that he cannot take the role of God. Therefore there is little need for much symbolism.
Yet one significant event does have metaphorical significance-Dantes' baptism of sorts when he is thrown into the sea by the prison guards. This event is truly a watershed experience for Dantes and the reader. It is at this time that Dantes changes to the Count of Monte Cristo. No longer is Dantes simply an innocent, young sailor hoping to make it in the world. Now he is a man grown hardened, bitter and distrustful, after aging in his dark prison cell for fourteen years.
Finding good in others and returning that good is not his goal; Dantes seeks revenge. In this way, Dumas sets the scene for the rest of his novel. The fascinating adventure story of the first few chapters has now grown sour and becomes a tale of vengeance, trickery and deceit. For it is this baptism which encourages Dantes to begin lying for the first time in his life (seen when the merchant ship picks him up and he lies about his identity).
Dumas also changes Dantes' character in terms of reader perception. Following his baptism, Dantes is no longer the clear-cut hero. He begins to use others for his own advantage--even forcing them into suicide at times. Indeed Dantes' "swim" has changed him, for better or worse.