Caesar enters a public square with Antony, Calpurnia, Portia, Decius, Cicero, Brutus, Cassius, Casca, and a Soothsayer; he is followed by a throng of citizens and then by Flavius and Murellus. Antony, dressed to celebrate the feast day, readies himself for a ceremonial run through the city. Caesar urges him to touch Calpurnia, Caesar’s wife, as he runs, since Roman superstition holds that the touch of a ceremonial runner will cure barrenness. Antony agrees, declaring that whatever Caesar says is certain to become fact.

The Soothsayer calls out from the crowd to Caesar, telling him to beware the Ides of March. (The “ides” refers to the fifteenth day of March, May, July, and October and the thirteenth day of the other months in the ancient Roman calendar.) Caesar pauses and asks the man to come forward; the Soothsayer repeats himself. Caesar ultimately dismisses the warning, and the procession departs. Brutus and Cassius remain. Cassius asks Brutus why he has not seemed himself lately. Brutus replies that he has been quiet because he has been plagued with conflicting thoughts. But he assures Cassius that even though his mind is at war with itself, he will not let his inner turmoil affect his friendships.

Cassius and Brutus speak together. Cassius asks Brutus if Brutus can see his own face; Brutus replies that he cannot. Cassius then declares that Brutus is unable to see what everyone else does, namely, that Brutus is widely respected. Noting that no mirror could reveal Brutus’s worthiness to himself, Cassius offers to serve as a human mirror so that Brutus may discover himself and conceive of himself in new ways.

Brutus hears shouting and says that he fears that the people want to make Caesar their king. When Cassius asks, Brutus affirms that he would rather that Caesar not assume the position. Brutus adds that he loves Caesar but that he also loves honor, and that he loves honor even more than he fears death. Cassius replies that he, too, recoils at the thought of kneeling in awe before someone whom he does not consider his superior, and declares, “I was born as free as Caesar, so were you. / We both have fed as well, and we can both / Endure the winter’s cold as well as he” (I.ii.99–101). Cassius recalls a windy day when he and Caesar stood on the banks of the Tiber River, and Caesar dared him to swim to a distant point. They raced through the water, but Caesar became weak and asked Cassius to save him. Cassius had to drag him from the water. Cassius also recounts an episode when Caesar had a fever in Spain and experienced a seizure. Cassius marvels to think that a man with such a feeble constitution should now stand at the head of the civilized world.

Caesar stands like a Colossus over the world, Cassius continues, while Cassius and Brutus creep about under his legs. He tells Brutus that they owe their underling status not to fate but to their own failure to take action. He questions the difference between the name “Caesar” and the name “Brutus”: why should Caesar’s name be more celebrated than Brutus’s when, spoken together, the names sound equally pleasing and thus suggest that the men should hold equal power? He wonders in what sort of age they are living when one man can tower over the rest of the population. Brutus responds that he will consider Cassius’s words. Although unwilling to be further persuaded, he admits that he would rather not be a citizen of Rome in such strange times as the present.

Meanwhile, Caesar and his train return. Caesar sees Cassius and comments to Antony that Cassius looks like a man who thinks too much; such men are dangerous, he adds. Antony tells Caesar not to worry, but Caesar replies that he prefers to avoid Cassius: Cassius reads too much and finds no enjoyment in plays or music—such men are never at ease while someone greater than themselves holds the reins of power. Caesar urges Antony to come to his right side—he is deaf in his left ear—and tell him what he thinks of Cassius. Shortly, Caesar and his train depart.

Brutus and Cassius take Casca aside to ask him what happened at the procession. Casca relates that Antony offered a crown to Caesar three times, but Caesar refused it each time. While the crowd cheered for him, Caesar fell to the ground in a fit. Brutus speculates that Caesar has “the falling sickness” (a term for epilepsy in Elizabethan times). Casca notes, however, that Caesar’s fit did not seem to affect his authority: although he suffered his seizure directly before the crowd, the people did not cease to express their love. Casca adds that the great orator Cicero spoke in Greek, but that he couldn’t understand him at all, saying “it was Greek to me” (I.ii.278). He concludes by reporting that Flavius and Murellus were deprived of their positions as civil servants for removing decorations from Caesar’s statues. Casca then departs, followed by Brutus.

Cassius, alone now, says that while he believes that Brutus is noble, he hopes that Brutus’s noble nature may yet be bent: “For who so firm that cannot be seduced?” he asks rhetorically (I.ii.306). He decides to forge letters from Roman citizens declaring their support for Brutus and their fear of Caesar’s ascent to power; he will throw them into Brutus’s house that evening.

While the opening scene illustrates Caesar’s popularity with the masses, the audience’s first direct encounter with him presents an omen of his imminent fall. Caesar’s choice to ignore the Soothsayer’s advice proves the first in a series of failures to heed warnings about his fate. Just as Caesar himself proves fallible, his power proves imperfect. When Caesar orders Antony to touch Calpurnia, Antony replies that Caesar need merely speak and his word will become fact—that is, Caesar’s authority is so strong that his word immediately brings about the requested action. However, while the masses may conceive of Caesar’s power thus, Caesar’s order to Antony alerts us to the reality that he and his wife have been unable to produce a child. The implication that Caesar may be impotent or sterile is the first—and, for a potential monarch, the most damaging—of his physical shortcomings to be revealed in the play.

This conversation between Brutus and Cassius reveals the respective characters of the two men, who will emerge as the foremost conspirators against Caesar. Brutus appears to be a man at war with himself, torn between his love for Caesar and his honorable concern for Rome. He worries that it is not in Rome’s best interest for Caesar to become king, yet he hates to oppose his friend. Cassius steps into Brutus’s personal crisis and begins his campaign to turn Brutus against Caesar, flattering Brutus’s pride by offering to be his mirror and thus relaying to him the ostensible high regard in which the citizens hold him.

Cassius compounds Brutus’s alarm about Caesar’s growing power with references to his weak physical state: he lacks stamina and is probably epileptic. But Cassius observes only Caesar’s frail human body, his private self. When he urges Brutus to consider that the name of Brutus should be as powerful as the name of Caesar, he fails to understand that Caesar’s real power is not affected by private infirmities but rather rests in his public persona, whose strength is derived from the goodwill and good opinion of the populace.

Caesar, on the other hand, shows much more perceptiveness in his analysis of Cassius; he observes both Cassius’s private and public personas and notices a discord. He is made uneasy by what appears to be Cassius’s lack of a private life—Cassius’s seeming refusal to acknowledge his own sensibilities or nurture his spirit suggest a coldness, a lack of human warmth. Caesar comments to Antony, “He loves no plays, / As thou dost, Antony; he hears no music. / Seldom he smiles, and smiles in such a sort / As if he mocked himself, and scorned his spirit / That could be moved to smile at anything” (I.ii.204–208). Cassius remains merely a public man, without any suggestion of a private self. Such a man, Caesar properly recognizes, is made uncomfortable by others’ power.

The question of Caesar’s own ambition is raised in Casca’s account of the triumphal procession. In describing how Antony offered Caesar a crown three times, Casca makes sure to point out Caesar’s reluctance in refusing the crown. Since the incident is related from Casca’s anti-Caesar perspective, it is difficult to ascertain Caesar’s true motivations: did Caesar act out of genuine humility or did he merely put on a show to please the crowd? Nevertheless, Casca’s mention of Caesar’s hesitation suggests that, no matter how noble his motivations, Caesar is capable of being seduced by power and thereby capable of becoming a dictator, as Brutus fears.

At the close of the scene, when Cassius plots to turn Brutus against Caesar by planting forged letters in Brutus’s house, Cassius has shrewdly perceived that Brutus’s internal conflict is more likely to be influenced by what he believes the populace to think than by his own personal misgivings. Cassius recognizes that if Brutus believes that the people distrust Caesar, then he will be convinced that Caesar must be thwarted. Cassius aims to take advantage of Brutus’s weakest point, namely, Brutus’s honorable concerns for Rome; Brutus’s inflexible ideals leave him open for manipulation by Cassius. Cassius, in contrast, has made himself adaptable for political survival by wholly abandoning his sense of honor.