First of all, the day is the Ides of March, a day against which a soothsayer has warned Caesar earlier in the play. Secondly, Caesar has been awakened by his wife Calpurnia crying out in her sleep from a dream; she begs Caesar not to go to the Senate in the morning when she speaks with him. And, thirdly, Caesar's servant returns from the augurers with the message of warning for him to remain inside because “They could not find a heart within the beast” (2.2.43). Nevertheless, Caesar interprets this finding differently, contending that"the gods do this in shame of cowardice," and it is only when Calpurnia goes on her knees and begs him that Caesar considers not going.
Knowing that it is the Ides of March, the conspirators worry that Julius Caesar will be afraid or will be warned about the dangers of attending the Senate. So Decius, as planned, arrives to accompany Caesar; however, Caesar tells him, "I will not come today." Then, as Caesar reveals his reason, Decius informs Caesar that this day he will be given a crown. How, he asks Caesar, can he tell the Seante that Caesar is afraid?
Having made Caesar feel foolish in his fears, in his pride, he asks for his robe; after he does so, Brutus and the others arrive in order to accompany him to the Senate.