In Caesar's house, Caesar is awakened by both the storm and by his wife Calpurnia's talking in her sleep. She has been dreaming of his murder. Caesar orders a servant to tell the priests to sacrifice animals to try and tell the future.
More evidence of Caesar's superstition. Calpurnia's apparent gift for prophecy aligns her with the supernatural elements of the play, and contrasts her with the logical Portia.
Calpurnia enters, telling Caesar he must not leave the house that day, but he insists that he will, since none would dare attack him. Calpurnia says that night watchmen have seen a lioness give birth in the streets, graves open and the dead walk, and blood rain on the Capitol. Caesar is still not swayed, saying that these omens could be intended for anyone, and that no-one can escape what the Gods have decreed. He adds that death should not be feared, since it must come when it will, and that "Cowards die many times before their deaths; / The valiant never taste of death but once" (2.2.32-3).
Caesar's ego makes him suspect that the omens are intended for him, but since this would conflict with his belief that he is invincible, he rejects the idea. In a way, Caesar is trapped: even if the omens do predict his death, he is compelled to disregard them, since seeming afraid would mean the "death" of Caesar as he sees himself.
The servant enters and says that the priests advise Caesar not to go to the Capitol, since they found no heart in the sacrificial animal. Caesar reinterprets this to mean that he would be a coward (heartless) to stay home, and adds that he is more dangerous than Danger itself.
Caesar must go to increasingly ridiculous interpretive lengths to reconcile the mounting supernatural evidence that he is in danger with his belief—or duty to act like—this is impossible.
When Calpurnia begs on her knees for Caesar to stay, he consents to send the message that he is sick, and remain at home. Decius enters, and Caesar tells him he will not go. When Calpurnia tells Decius to say Caesar is sick, Caesar says that he should not have to make excuses, and that his will should suffice as a reason.
Calpurnia, unlike Portia, kneels to beg rather than as a formality. Caesar must contradict his earlier agreement to make an excuse, since needing to lie to the Senate would indicate that they have power over him.
Decius entreats Caesar for an explanation, and Caesar admits that Calpurnia was frightened by a dream where a statue of him spurted blood that Romans bathed in. Decius reinterprets this as a good omen, signifying that Rome draws its life from Caesar, adding that the Senators may mock Caesar for listening to his wife, and whisper that he is afraid to come.
Other characters misinterpreted omens based on information they lacked, but Decius lies about an omen based on information he has. The idea that it's shameful for Caesar to be influenced by his wife underscores the masculinity of Roman culture.
Caesar decides to go to the Capitol after all. Cassius, Brutus, Ligarius, Metellus, Casca, Trebonius, and Cinna enter to escort him. Antony enters a moment later, and Caesar teases him about being up late partying. Caesar suggests they all share some wine, and then leave together. Aside, Brutus laments what he and his fellow conspirators are about to do.
The joke about Antony's reputation for being fun-loving supports the idea that he is harmless. Conversely, Brutus, who has appeared coldly steadfast in front of the others, is privately in pain over their approaching deed.