"Beware the ides of March...."See in text(Act I - Scene II)
The "ides of March" is March 15th. Each month has an "ides," or middle of the month, but the ides of March became famous because it is the day in which Caesar was assassinated. This bit of foreshadowing has become one of the most famous lines in this play. Caesar hears two warnings from this soothsayer, someone who can see and predict the future, and a warning from a dream his wife has that something bad will happen to him on March 15th. However, Caesar ignores these warnings and ventures out unprotected on this day anyway. This shows that Caesar believes in his own power: he thinks that his is impervious to prediction, danger, and the will of the gods.
"My heart laments that virtue cannot live
Out of the teeth of emulation...."See in text(Act II - Scene III)
Artemidorus characterizes Caesar as virtue personified and the conspirators as emulation. In this case, “emulation” refers to rivalry or competition rather than imitation.
"And Caesar's spirit ranging for revenge,(290)
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,..."See in text(Act III - Scene I)
Here, Antony reveals his true rage over Caesar's murder. Up until this point, Antony has remained calm, presenting Caesar as a bad man who did not deserve to die. In private the audience sees his true feelings. He invokes Caesar's ghost and the goddess of ruin, Ate, to wreak havoc on Cassius and Brutus. The "dogs of war" embody the type of animalistic and vicious warfare that Antony wants to wage against Caesar's assassins.
"disposing of new dignities...."See in text(Act III - Scene I)
That is, "handing out political offices."
This line reveals how Cassius is already thinking about money and other perks that can be obtained by the "disposing of new dignities." That he thinks this here also reveals that he's been considering these advantages likely since he first began plotting against Caesar.
"Cassius, go you into the other street
And part the numbers...."See in text(Act III - Scene II)
By referring to the public as “the numbers,” Brutus reiterates the idea that the citizens of Rome are a means to an end. To Brutus and Cassius, the public are simply a number that needed to be swayed in order to advance their political agenda.
"This was the most unkindest cut of all;
For when the noble Caesar saw him stab,..."See in text(Act III - Scene II)
"Unkind" in Shakespeare's time meant unnatural, ungrateful, and degenerate. Antony uses these words to blame Caesar's death on Brutus's character: in essence, it was not the stab wound that killed Caesar, but Brutus's betrayal. Antony's memorial for Caesar quickly becomes a character assassination of Brutus.
"And bay'd about with many enemies;..."See in text(Act IV - Scene I)
Octavius echoes Antony’s famous turn of phrase from Act III, Scene I. Leaning over Caesar’s bloodied body, Antony calls for the crowd to “Cry ‘Havoc!’, and let slip the dogs of war” (273). While Antony intended to release the Roman public on the conspirators like a pack of hounds, Octavius now characterizes those same conspirators as dogs “bay[ing]” at him and Antony.
"their names are prick'd...."See in text(Act IV - Scene I)
This is a clever reversal. To say the conspirators names are “prick’d” means they are marked by the pen for death, but specifically in a way that calls to mind Caesar’s stabbing.
"I'll use you for my mirth, yea, for my laughter,
When you are waspish...."See in text(Act IV - Scene III)
“Waspish” means wasp-like, irritable, easily offended, choleric. In this passage Brutus displays a delight in provoking and teasing Cassius, which is surprising given Brutus’s serious nature.
"Must I give way and room to your rash choler?
Shall I be frighted when a madman stares?..."See in text(Act IV - Scene III)
Brutus cites the ancient system of medicine in which the human body was understood to be organized by four balancing “humors”: melancholia, cholera, phlegma, and sanguis. Each humor was associated with an element, a bodily fluid, and a temperament. By accusing Cassius of being choleric, Brutus is calling the man irritable and cranky.
"Must I give way and room to your rash choler?
Shall I be frighted when a madman stares?..."See in text(Act IV - Scene III)
Brutus cites the ancient system of medicine in which the human body was understood to be organized by four balancing “humors”: melancholia, cholera, phlegma, and sanguis. Each humor was associated with an element, a bodily fluid, and a temperament. By accusing Cassius of being choleric, Brutus is calling the man irritable and cranky.