One of the themes that is important not just in Act II but in the whole play is that of the corrupting influence of power. In Act II scene 1, Brutus discusses the potential for corruption that he fears in Julius Caesar, thinking that if he were not opposed at this stage, he would come to "scorn the base degrees" and forget his empathy and compassion for the people that helped raise him to his position of power and strength. Brutus therefore debates that it might be the best thing to kill him now, and resolves to see him in a particular way, comparing him to a serpent who is not yet hatched:
And therefore think him as a serpent's egg
Which, hatch'd, would, as his kind, grow mischievous,
And kill him in the shell.
The reference to the theme of the corruption power in this quote is clear, and yet also problematic. It is very difficult to state with any certainty that a given person will become corrupted by their power, even though experience would suggest that is the case. The analogy of Brutus in this instance might therefore be seen to be trying to justify a crime that his conscience is troubled by. Brutus tries to make himself believe that Caesar is a figure who will definitely become corrupted and turn evil, but through developing this analogy he opens himself up to similar arguments, as he has to debate whether his desire to topple Caesar is more to do with his own temptation to seize power than it is merely to altruistically serve Rome. The corruption of power works both ways, whether or not Brutus is explicitly aware of it.