"Beware the Ides of March."
As early as the first act, Caesar is warned about his impending murder from a soothsayer who cautions him against the date March 15 (now famously known as the day Caesar was murdered by the senators). Caesar ignores the soothsayer's warning, dismissing him as mentally unstable. This encounter with the soothsayer, who appears twice before Caesar is murdered, establishes a pattern by which Caesar fails to heed the obvious warning signs that lead to his demise. Caesar's choice to go to the senate anyway on March 15 showcases his sense of pride and his ego over having gained so much power.
"Men at some time are masters of their fates.
The fault, dear Brutus, is not in our stars
But in ourselves, that we are underlings."
Here, Cassius argues to Brutus that one's destiny is not in fact shaped by gods or the heavens but by the individual. Cassius is slowly attempting to convince Brutus to join the conspiracy to kill Caesar, and he here uses his rhetorical skill to convince Brutus that he must take control over his own life and the figurative life of Rome.
"Cowards die many times before their deaths,
The valiant never taste of death but once. "
Caesar speaks these words to his wife, Calpurnia, after she reveals that she had a dream about him being mortally wounded. When Calpurnia attempts to get Caesar to stay home rather than go to the senate on March 15, he responds by declaring the notion a cowardly one and comparing cowards to people who die many times (in reputation) before they die physically.
"But I am constant as the Northern Star,
Of whose true fixed and resting quality
There is no fellow in the firmament."
Julius Caesar delivers this speech just before he is stabbed to death by the Roman senators. Here, he compares himself to the north star, suggesting that he is unassailable and infinite in terms of constancy. The speech is ironic because almost immediately following its delivery, Caesar dies.
"Et tu, Brute? – then fall, Caesar."
These are the last words that Julius Caesar speaks before he dies, and they are significant because they express his shock, surprise, and dismay over realizing that Brutus, his friend, has taken part in the murder. The delivery of this line suggests that Caesar dies willingly once it becomes clear he has been betrayed by his good friend. The line has become famous in popular culture as a means of declaring that one has been misled by a supposed ally.
"Not that I loved Caesar less, but that I loved Rome more."
In his eulogy for Caesar, Brutus convinces the common people that he took part in the conspiracy because he was concerned about what Caesar's increasing power would mean for Rome's future. He here admits to betraying his friend, but argues that he did so because he loved Rome more than he loved Caesar. In many ways, Brutus delivers an honest eulogy that reflects his idealism over Rome and how it is governed.
"And Brutus is an honourable man."
Brutus allows Antony to also deliver a eulogy for Caesar, despite warnings from other senators not to allow him to speak. Antony's speech is often regarded as one of the most famous in all of Shakespeare's oeuvre, as it is a masterclass in the power of rhetoric: purporting to express deference toward the other senators (like Brutus), Antony ultimately reveals to his listeners that the senators betrayed a benevolent ruler and are not, in fact, honorable in the least.
"He must be taught, and trained, and bid go forth—
A barren-spirited fellow, one that feeds
On objects, arts, and imitations,
Which, out of use and staled by other men,
Begin his fashion. Do not talk of him
But as a property."
Here, Antony makes remarks about Lepidus to Octavius as the men will ultimately form the Second Triumvirate together. Antony compares Lepidus to a horse that must be trained and act according to its owner's bidding. Here, Antony seems to devalue Lepidus as a political ally at the same time he sees him as a loyal and consistent military operative, which was in itself a valuable position for Rome.
"There is a tide in the affairs of men
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries."
Here, Brutus is attempting to convince Cassius that it is time to begin the war with Antony and Octavius. He compares men's fate to a body of water and argues that they must follow the tide or ultimately perish. Though he is speaking about the impending war, Brutus's words are also relevant for his actions earlier in the play, when he made the decision to betray Caesar and murder him, ultimately ensuring his own demise in the process.
"This was the noblest Roman of them all."
At the end of the play, Antony comes upon Brutus's body and makes this remark. This quotation highlights both Antony's balanced and realistic nature – despite having fought Brutus, he still values him as a servant of Rome – as well as a central truth about Brutus's character. Though Brutus betrayed Caesar, Antony here recognizes that he did it out of loyalty to Rome and fear over what Caesar's reign could mean for the empire. As such, Antony credits Brutus with the title "the noblest Roman of them all" to acknowledge how Brutus's idealism led him to this point.