In act 2, scene 2, Calpurnia pleads with Caesar not to travel to the Senate on account of poor omens and her prophetic dream, successfully swaying him with her pleas. This changes, however, with the arrival of Decius, who is able to convince Caesar to act otherwise.
Ultimately, Decius's success depends on an appeal to Caesar's pride and vanity. He interprets Calpurnia's dream (in which she saw a bleeding statue of Caesar, with Roman citizens washing their hands in the blood) in a manner more pleasing to Caesar's ego. Decius claims that this image of the bleeding statue, rather than being a portent of doom, is actually a testament to Caesar's greatness:
Your statue spouting blood in many pipes,
In which so many smiling Romans bathed,
Signifies that from you great Rome shall suck
Reviving blood, and that great men shall press
For tinctures, stains, relics and cognizance. (2.2.85–89)
Indeed, it might also be worth noting that in this passage, Shakespeare seems to be invoking imagery associated with early modern monarchy, by which kings were often believed to possess healing powers and the sick would gather around them in the hopes of receiving healing. It is an interpretation that flatters Caesar's ego and sense of self-importance.
At the same time, Decius also utilizes shaming tactics against Caesar. He goes on to tell Caesar that, while the Senate had intended to provide Caesar a crown, they might take back that honor if Caesar does not arrive. Indeed, he goes on to say, such a decision could even make Caesar an object of derision:
Besides, it were a mock
Apt to be render'd, for someone to say,
"Break up the senate till another time,
When Caesar's wife shall meet with better dreams.
If Caesar hide himself, shall they not whisper,
"Lo! Caesar is afraid?" (2.2.96–101)
Through these tactics, Decius is ultimately able to bend Caesar to his will. He convinces Caesar to attend the Senate, thus walking to his own destruction.