One might suppose that this was a Shakespearean invention, introduced for dramatic effect, for the chance of turning lights low, producing shadows, and chilling the audience, but, in actual fact, Shakespeare does not have to invent it. The report that Caesar's ghost appeared to Brutus is to be found in Plutarch.
It is with a forward look to this scene, perhaps, that Shakespeare had had Mark Antony speak earlier of "Caesar's spirit."
The fifth act opens in the plains near Philippi, with the opposing armies facing each other and waiting for battle. Octavius, looking at the scene with grim satisfaction, says:
—Act V, scene i, lines 1-4
What had happened between the acts was this. Brutus and Cassius, crossing the straits into Macedonia from Asia Minor, encountered a portion of the triumvir army near Philippi. If the conspirators had attacked at once, they ought to have won, but before they could do so, the rest of the triumvir army arrived and it was a standoff.
The triumvir army now outnumbered the conspirators but was weaker in cavalry. What is more, it was Brutus and Cassius who had the strong position in the hills, while Antony and Octavius occupied a marshy and malarial plain.
Brutus and Cassius had only to stay where they were. It would have been suicidal for Antony and Octavius to try to charge into the hills. Yet to stay on the plains would expose them to hunger and disease.
Indeed, Octavius was already sick, although this doesn't appear in the play. Octavius seemed always to be sick before a battle. In this case, he fell sick at Dyrrhachium (on the coast of what is now Albania) and had to be carried by litter the 250 miles to Philippi.
Cassius opposed battle, maintaining that by waiting it out, the enemy would sooner or later have to retreat and that the effect would be one of victory for the conspirators. He was manifestly correct in this and Antony, putting himself grimly in the conspirators' place, was sure that was exactly what they would do.
Antony still did not count on the egregious stupidity of Brutus. Brutus again opposed Cassius and favored immediate battle. Once again Brutus insisted on having his way. Once again Cassius gave in.
A parley between the opposing commanders was arranged before the battle. Perhaps an accommodation could be arranged. That could not be, however, for the conversation quickly degenerated into recriminations. At one point, Cassius refers bitterly to Antony's oratory (thinking perhaps of the funeral speech) and says:
—Act V, scene i, lines 34-35
Hybla was a town in Sicily, on the southern slopes of Mount Etna, and some forty miles northwest of Syracuse. It was famous, almost proverbial, for its honey.
In the wordy quarrel, Antony does have the best of it and Cassius finally is forced to become aware of Brutus' misjudgments. He says to Brutus angrily:
—Act V, scene i, lines 45-47
Surely he must have thought how, in all likelihood, the conspirators would have been long in control of Rome if only Antony had been killed along with Caesar, as he had advised.
There is nothing, then, but to make ready for the actual battle. Cassius is seriously depressed, perhaps because it has been borne in upon him, forcefully, how wrong Brutus has been all through, and because he bitterly regrets all the times he gave in wrongly.
It is now October 42 b.c., more than two and a half years since the assassination of Caesar, and Cassius says to his aide:
—Act V, scene i, lines 70-72
Since we don't know in what year Cassius was born, we can't say how old he was on the day of the Battle of Philippi. However, Plutarch refers to him as older than Brutus (a view Shakespeare adopts) and Brutus may have been born in 85 b.c. It would seem then that Cassius must be in his mid-forties at least and possibly pushing fifty.
Cassius does not find the fact that the battle will be fought on his birthday to be a good omen. He does not want to fight it. He says to Messala:
—Act V, scene i, lines 73-75
This is a reference to the fact that it is Brutus, not Cassius, who is pushing for battle. Cassius, who let himself be overruled, reminds himself, sadly, that Pompey was similarly forced into battle at Pharsalia, six years before, by the hotheads among his councilors, when cautious delay might have served his cause better.
To unavailing regret that he had allowed himself to be swayed by Brutus, Cassius finds trouble in supernatural omens. He says:
—Act V, scene i, lines 76-78
Epicurus of Samos was a Greek philosopher who was a contemporary of the Zeno who had founded Stoicism. Epicurus' philosophy (Epicureanism) adopted the beliefs of certain earlier Greek philosophers who viewed the universe as made up of tiny particles called atoms. All change consisted of the random breakup and rearrangement of groups of these atoms and there was little room in the Epicurean thought for any purposeful direction of man and the universe by gods. Omens and divine portents were considered empty superstition.
Now, however, Cassius begins to waver. It seems two eagles, having accompanied the army from Sardis to Philippi, have now flown away, as though good luck were departing. On the other hand, all sorts of carrion birds are now gathering, as though bad luck were arriving.
Cassius' pessimism forces him to question Brutus as to his intentions in case the battle is lost. Brutus answers in high Stoic fashion. His actions will follow: