Cassius does not agree with Casca about the storm and the omens. In fact, Cassius appears to be absolutely fearless in regards to the strange events. Casca meets Cassius after he is has just left Cicero. Cassius is “unbraced” (48): his doublet (or jacket) is open. Cassius is daring the gods to strike him with their lightning. Cassius does not truly believe that the strange events have any significance at all. He claims that only “old men, fools, and children calculate” or believe in them as omens (line 65). Cassius is suggesting that he is above such forces. He believes himself to be above the power of fate (not unlike the character of Iago in Othello). But like Iago, Cassius will later learn that no one is actually superior to the force of fate.
Cassius then suggests an alternative interpretation. He states that if the strange events do have any meaning, then they concern Caesar himself. The “monstrous quality” of nature relates to the “monstrous state” (lines 68-71). By the word state, Cassius is referring to the government of Rome in general and to Julius Caesar specifically. Omens do not relate to the common man, Cassius believes, but only to kings and rulers. Cassius thus interprets the events or omens, if they have any meaning at all, to indicate the success of his plot to assassinate Julius Caesar.
Cassius convinces Casca to join his conspiracy (see line 119). Cassius explains to Casca that death is preferable to a life of tyranny:
I know where I will wear my dagger then:
Cassius from bondage will deliver Cassius.
(88-89) That part of tyranny that I do bear
I can shake off at pleasure. (98-99)
Cassius is exclaiming that he will kill himself with his own knife or dagger before he allows himself to live a life of slavery or bondage under the rule of Caesar. Cassius is arguing that the conspirators have nothing to lose and everything to gain. If they succeed in assassinating Caesar, they will have freedom. If they do not succeed, then they can still kill themselves and avoid a life of slavery. In essence, then, he is saying that they should either kill Caesar or themselves. Given those two choices, Casca can only agree with Cassius.
The final lines of the scene are devoted to Cassius talking to Casca and Cinna (another
conspirator) about their plot to assassinate Caesar. Cassius gives the phony letters to Cinna (line 142) so that Cinna can place them around Brutus’ house. Cassius also informs Casca that Brutus will be joining the conspiracy: “Three parts of him is ours already” (154-55). Cassius is saying that Brutus is already three-fourths (or 75%) convinced to join, and the fake letters will convince him the rest of the way. Cassius is a shrewd man, and he is not wrong about Brutus.
Casca is pleased that Brutus will be joining the conspiracy, and he uses a simile to alchemy to indicate how valuable Brutus will be:
… that which would appear offence in us His countenance, like richest alchemy, Will change to virtue and to worthiness.
(158-60)
By this, Casca means that people will consider the assassination as a virtuous and worthy act if Brutus plays a part in it. Otherwise, people will view the act as sinful or criminal. Without Brutus, the other conspirators would most likely end up being executed for the crime of killing Caesar. But with Brutus, the conspirators could become the new rulers of Rome.
One man does make a significant difference in this case.
Shakespeare is thus illustrating how acts of political violence can be viewed in either a positive or negative manner depending on minor details. The public will not view the act of murder itself as either positive or negative. They will instead look at the motivation (or what they believe to be the motivation)
of the murderers. They will view the “why” as being more important than the “what.” After the assassination is over, Shakespeare will explore this idea of public perception in greater detail. When Brutus makes a speech to the citizens of Rome, the people then perceive the act in a positive manner. But, later, when Antony makes a speech, their perception changes. The act of murder remains the same either way. What has changed is the people’s perception as to the motivation of the act.