Julius Caesar and the Supernatural

There is an element of the supernatural in just about all of Shakespeare's work, and Julius Caesar is no different.  There are omens or signs that Shakespeare uses as foreshadowing to Caesar's murder that the characters all misinterpret as good signs.
In Act I, scene iii, a terrible storm is the backdrop for Cassius' and Casca's conversation.  Cassius compares Caesar to to the storm, calling him dark and terrified as the storm.  Cassius sees the storm as a bad omen for Caesars coronation, that his promotion will lead to bad things for the state.  Cassius does not see that the storm is used to reveal his own darkness and plots.  Casca warns him not t walk in the storm, but Cassius ignores him saying that there is not difficulty for honest men, though this aligns Cassius with the evilness of the storm and his own plots.

Caesar's wife, Calpurnia experiences the next omen. In Act II scene iii, Calpurnia dreams of Caesars statue with holes in it and blood pouring out from those holes.  She believes that she is seeing signs of her husband's murder and begs him not to go to the senate meeting.  She also dreams of dead people walking in the streets, ghosts, a lioness giving birth, and a terrible storm.  Caesar heeds her warnings by seeing to an animal sacrifice so the augers may read the entrails.  Upon doing this, they cannot find the animal's heart, a very bad sign.  Caesar does not believe that the gods bode ill of him, so he ignores his wife and goes to the senate.

Act IV scene ii ends with Brutus seeing the ghost of Caesar, who tells him that he will see Brutus in Philippi.  Shakespeare uses the ghost as a symbol and as foreshadowing because Brutus dies at Philippi.  The ghost is used to symbolize Brutus' guilt from the murder of his friend in cold blood.