In Act 1, Scene 2, Cassius tells stories of Caesar's supposed weakness in order to pit Brutus against him. At one moment, Cassius describes a time in which he saved Caesar from drowning. He makes his point through simile and an allusion to the story of the epic hero, Aeneas:
Caesar cried “Help me, Cassius, or I sink!”
I, as Aeneas, our great ancestor,
Did from the flames of Troy upon his shoulder
The old Anchises bear, so from the waves of Tiber
Did I the tired Caesar.
Aeneas and his father, Anchises, are two legendary figures in Greco-Roman myth. Homer mentions Aeneas in the Iliad, but the hero eventually gets an epic of his own in Virgil’s Aeneid. The poem tells the story of Aeneas’s escape from Troy in the aftermath of the Trojan war, and his journey across the Mediterranean to the Italian peninsula where he eventually founds Rome. Shakespeare’s allusion mirrors the structure of epic poetry, as well: Cassius makes this comparison in the form of the very sort of epic simile (a multi-line simile with the general structure of “as… so…”) that might be found in the Iliad, the Odyssey or the Aeneid.
Shakespeare’s allusion to the stories of the Aeneid would appear to be an anachronism, as Virgil wrote the poem decades after Caesar’s death. This may have been deliberate, however, as there is a complex interrelation between the Julius Caesar, Virgil’s motivation for writing the Aeneid, and the circumstances surrounding Shakespeare’s composition of his own version of events in Julius Caesar.
Historically, the assassination of Julius Caesar (depicted in Julius Caesar) led to a series of political upheavals in Rome that dissolved the Roman Republic and transformed it into the Roman Empire. The first Roman Emperor, Caesar Augustus (the character Octavian in the play), is Julius Caesar’s great-nephew. Virgil writes the Aeneid during Augustus’s reign and weaves references and critiques of his regime into the fabric of the epic poem.
In much the same manner, Shakespeare writes Julius Caesar during the Elizabethan period to offer a critique of the state of England at the time. By alluding to the Aeneid in Julius Caesar, Shakespeare therefore makes a self-conscious reference to literature’s ability to speak truth to power. Never one to miss a chance for irony, however, Shakespeare gives this allusion to Cassius: in casting his criticism of Caesar in terms of Aeneas and Anchises, Cassius anachronistically references the literary world of the Roman Empire that will come about as a result of his impending assassination of Caesar. Even as he claims to preserve the Roman Republic by killing Caesar, he hastens its descent into empire.
In Act 1, Scene 2, Cassius shows his disdain for Caesar as Brutus and he remark on the crowd's ecstatic reception of Caesar's victory over Pompey. He makes an allusion alludes to the Colossus of Rhodes, one of the Seven Wonders of the Ancient World, to describe Caesar's perceived stature over his peers:
I do believe that these applauses are
For some new honors that are heaped on Caesar.
Why, man, he doth bestrie the narrow world
Like a Colossus, and we petty men
Walk under his huge legs and peep about
To find ourselves dishonorable graves.
The Colossus of Rhodes was a massive statue, thought in Shakespeare's time to have once stood straddling the opening of the harbor of the Greek island of Rhodes. Caesar has become a Colossus, Cassius argues, and everyone else must pass underneath him like "petty men"—poor mortals left to scamper about and clean up in the wake of Caesar's destruction.
By painting Caesar as a Colossus, who makes the rest of Rome's political class look small and weak, Cassius casts Caesar as a threat to his fellow politicians' manhood if he continues to amass power. As Shakespeare explores the power of speech to affect political sentiment, Cassius's ability to appeal to the insecurities and doubts of his peers—and to the importance of manhood and honor as prime virtues—stands out as a particularly effective mode of persuasion.
In Act 3, Scene 1, Antony kneels by Caesar's dead body and offers a grief-filled soliloquy as tribute to his fallen friend. He makes a prophecy that Rome will plunge into a time of war, and alludes to classical mythology as he predicts how Caesar's ghost will come back for revenge:
And Caesar’s spirit, ranging for revenge,
With Ate by his side come hot from hell,
Shall in these confines with a monarch’s voice
Cry “Havoc!” and let slip the dogs of war,
That this foul deed shall smell above the earth
With carrion men groaning for burial.
"Ate" is an allusion to the Greek goddess Atë. According to Hesiod’s account of the Greek pantheon, Theogeny, she is the goddess of Ruin or destruction. For Caesar to return with Ate by his side, as Antony predicts, would mean the potential end of Rome or at least its descent into chaos. This sort of classical allusion tethers Julius Caesar to its historical source material. Antony’s appeal to the Greco-Roman pantheon would have reminded the contemporary audience of the distance between Elizabethan England and Caesar’s time, and therefore made it safer for Shakespeare to use his play to critique the politics of the time and forewarn the English population of the dangers of political power struggles.
In Act 5, Scene 1, Cassius, Brutus, and Antony trade insults as their armies face each other in battle. Cassius makes an allusion to Hyblean honeybees as he mocks Antony for his bluster:
The posture of your blows are yet unknown,
But, for your words, they rob the Hybla bees
And leave them honeyless.
Not stingless too.
O yes, and soundless too,
For you have stolen their buzzing, Antony,
And very wisely threat before you sting.
Hybla is an area of Sicily renowned for its bees. Cassius and Brutus use this allusion to insult Antony for his flowery language and lack of decisive action as a warrior: Antony has taken the “honey” from the Hybla bees and used it in his sweet speech, and has also “stolen their buzzing”: he makes a lot of noise with his words without any actual aggression, like a Shakespearean post-classical version of the idiom “all bark and no bite.” These jabs from Cassius and Brutus are direct attacks on Antony’s fitness as a soldier and political and military leader, reflecting both Cassius's preoccupation with status and Brutus's preoccupation with honor.