Shakespeare derived virtually all the historical information he used in his play from Plutarch's "Life of Julius Caesar," "Life of Brutus," and "Life of Antony." Both Calpurnia and Portia are frequently mentioned in these histories, so it was natural that Shakespeare should include them in his play. Besides that, there are too many male characters. It is impossible to keep them all straight in one's mind. Shakespeare needed some female characters (albeit played by young males) just for contrast and variety. He had actors in his company who specialized in female roles and he wanted to make use of them. (It seems possible that both Calpurnia and Portia, who never appear together, may have been played by the same young female impersonator wearing different wigs and different gowns.)
Calpurnia is important because of her dreams and her urging her husband to stay at home on the Ides of March. This comes straight out of Plutarch. An example of how Shakespeare dramatizes what he learned from Plutarch is seen in the following from Act 2, Scene 2:
Caesar, I never stood on ceremonies,
Yet now they fright me. There is one within,
Besides the things that we have heard and seen,
Recounts most horrid sights seen by the watch.
A lioness hath whelped in the streets;
And graves have yawn'd, and yielded up their dead;
Fierce fiery warriors fight upon the clouds,
In ranks and squadrons and right form of war,
Which drizzled blood upon the Capitol;
The noise of battle hurtled in the air,
Horses did neigh and dying men did groan,
And ghosts did shriek and squeal about the streets.
O Caesar! These things are beyond all use,
And I do fear them.
Portia is important mainly because she gives Brutus someone to talk to about his conflicting feelings. Otherwise Shakespeare might have had to resort to more soliloquies, which may be eloquent but are not dramatic. In Act 2, Scene 1, Portia finally gets her husband to promise to tell her everything about what is worrying him. Here is an example of her persuasive power.
Is Brutus sick, and is it physical
To walk unbraced and suck up the humors
Of the dank morning? What, is Brutus sick,
And will he steal out of his wholesome bed
To dare the vile contagion of the night
And tempt the rheumy and unpurged air
To add unto his sickness? No, my Brutus,
You have some sick offense within your mind,
Which by the right and virtue of my place
I ought to know of; and, upon my knees,
I charm you, by my once commended beauty,
By all your vows of love and that great vow
Which did incorporate and make us one,
That you unfold to me, yourself, your half,
Why you are heavy, and what men tonight
Have had resort to you; for here have been
Some six or seven, who did hide their faces
Even from darkness.
Both Calpurnia and Portia love their husbands and are utterly dependent upon them. They both provide interesting exchanges of dialogue between husbands and wives, building audience sympathy as well as creating suspense. Calpurnia is not successful in persuading her husband to stay at home that fatal day, but the outcome shows she was totally correct in her fears and premonitions.
Portia does not attempt to persuade Brutus to abandon his role in the plot to assassinate Caesar, but she does learn all about it from him in a conversation which is assumed to have taken place offstage. Onstage he tells her:
Portia, go in awhile,
And by and by thy bosom shall partake
The secrets of my heart.
All my engagements I will construe to thee,
All the charactery of my sad brows.
Leave me with haste. II.i
She has become a co-conspirator--something he probably wanted to avoid by concealing everything from her. In Act 4, Scene 4 she is in an emotional turmoil because now she knows all about the attempt that will shortly be made on Caesar's life. This scene is very effective because she is a weak, helpless woman who is burdened with direct and complete knowledge of what is about to happen. This is in contrast to Calpurnia who only has dreams and premonitions. But both women serve to build tension up to the point where the conspirators encircle Julius Caesar and stab him to death.
The primary female roles in Shakespeare’s The Tragedy of Julius Caesar are those of Calpurnia, wife of Caesar, and Portia, wife of Brutus.
These female characters serve to heighten the effect of suspense and fateful doom that hang over the characters of Brutus and Caesar as the play moves toward its tragic culmination.
In Act II Scene I Portia presses Brutus for an explanation of his troubling behavior. At this point she does not know that Brutus is planning to lead a conspiracy against Caesar. The fact that she is devoted enough to actually stab herself in the leg to get Brutus’ attention emphasizes the significance of their relationship. Later, while Brutus is away with his army, she commits suicide in her distress over his absence.
In Act II Scene II Calpurnia is the cautious voice of reason that Caesar should, but does not, heed. She warns him passionately not to go to the capitol folloowing a night of strange supernatural occurrences. At one point she has convinced him to agree to remain home, but shortly others arrive and use his pride and vanity against him to shame him into leaving the house and walking off to his death, unaware that his wife has been right all along.
By the end of the play it isn’t hard to imagine that Shakespeare is hinting that the hot blooded males should have listened to their wives. When the spouses are separated, they encounter danger that they cannot overcome on their own.