In Act 2 of Julius Caesar, why does Calphurnia want Caesar to remain at home?

In Act 2, Scene 2 of the play, tension mounts not only among the conspirators but also between Caesar and his wife Calphurnia.  The scene takes place on the dawn of Caesar's assassination, and Calphurnia's warnings to her husband are part of his "last chance" to survive.  Calphurnia bases her first appeal to her husband upon the storm the night before.  After describing the strange night filled with lions in the streets, graves giving up their dead, and fiery warriors, she states, "O Caesar, these things are beyond all use,/ And I do fear them!"

After this appeal fails with Caesar, Calphurnia argues that Caesar will not look like a weakling if he refuses to go to the Senate; she wants him to blame his absence on her.  She tells him, "Do not go forth to-day: call it my fear."

Finally, Calphurnia's final reason was that she had had a bad dream the night before in which Caesar's statue was pouring blood and that the Romans were celebrating and bathing their hands in Caesar's blood.  Caesar actually tells Decius Brutus (one of the conspirators) about the dream, but Decius Brutus reinterprets the dream and convinces Caesar to go.