In Julius Caesar by William Shakespeare, Cassius is the primary instigator of the assassination plot to kill Julius Caesar. Along with several other Roman senators, Cassius will murder Caesar at the forum on the Ides of March, as foretold by the soothsayer. Historically, this is an actual occurrence.
Cassius is a masterful manipulator. As the antagonist in the play, Cassius has determined to stop Caesar. In contrast to Brutus, Cassius's motives are not high-minded nor selfless. Consumed with envy of Caesar's rise to power, Cassius must enlist Brutus, a man loved and trusted by Caesar.
In Scene iii, Act 1, it is the night before Caesar's first appearance in the Senate as Emperor of Rome. Filled with thunder, lightning, and mystical portents, Cassius, Cinna, Casca (Roman Senators) meet in a street to discuss the plot. Cassius entices Casca to commit to the assassination. The discussion further details a meeting to be held later in the night at Pompey's statue--ironic because Caesar was responsible for the death of Pompey--to finalize the plans for the next day's exploit. To substantiate his commitment, Cassius shows himself unafraid of this terrible night and invites and dares the gods to strike him with lightning if he is not on the right path. To Cassius, this night is like Caesar: a man like anyone; a man grown too big; a man with too much power.
Cassius is angry. He feels that the Romans have become weak and womanish. Declaring that he will remove himself from this usurper of power, he declares:
Cassius from bondage will deliver Cassius.
Nothing and no one will enslave Cassius. Foreshadowing tomorrow's event, he refers to the dagger that he will use to kill Caesar.
Cassius beseeches the gods to explain why Caesar has been granted this great power:
Should Caesar be a tyrant then:
Poor man! I know he would not be a wolf
But that he sees the Romans are but sheep.
To Cassius, the Romans have become like trash if they worship someone so evil as Caesar.
Checking Casca's commitment to the cause, Cassius baits the weaker man by asking him if he is willing to become a slave to Caesar. Cassius, to ensure Brutus' complicity, asks Cinna to complete a task:
...take this paper,
And look you lay it in the praetor's chair,
Where Brutus may but find it; and throw this
In at this window; set this up with wax
Upon old Brutus' statue.
Cassius names other senators involved with the conspiracy. The scene ends with Cassius and Casca going to the conspiratorial meeting. To set, the scene for Act II, Cassius promises to go to Brutus' house and persuade him to join the others. Through the conversation in Act I, Cassius knows that part of Brutus dislikes Caesar's power; now, he must have Brutus completely.