Due to the importance of the classics in Elizabethan education, the audience of William Shakespeare's "Julius Caesar" would have been familiar with both the character and the historical setting before watching the play.
In Scene 1 we learn of the essential political strength of Caesar, that he is beloved by the plebs, or the common populace, something we find out when the cobbler admits to being out on the street to "make holiday to see Caesar and to rejoice in his triumph." Flavius' response indicates that Caesar is considerably less popular among patricians, in part because of his unwillingness to share power. He describes Caesar as one who "would soar above the view of men,/And keep us all in servile fearfulness."
When Caesar himself appears, both his popularity and his arrogance are confirmed. Cassius' speeches give the audience more details on how Caesar, rather than treating other aristocrats as equals, tends to treat them as his inferiors. Caesar's dismissal of the soothsayer who warns him "Beware the Ides of March" also suggests arrogance, something that will be confirmed by his determination to go to the forum, expressed to Calpurnia in Act 2:
Caesar shall forth: the things that threaten me
Ne’er look but on my back; when they shall see
The face of Caesar, they are vanished.
Caesar's main speech in Act 1 shows him to be capable of careful thought and analysis, as he correctly says of Cassius:
Such men as he be never at heart’s ease
Whiles they behold a greater than themselves;
And therefore are they very dangerous.
Despite this strength, the ability to read character and perceive danger, Caesar has a corresponding weakness of stubbornness and a sense of destiny, which prevents him from acting upon his perceptions: "I rather tell thee what is to be fear’d/Than what I fear, for always I am Caesar." The concluding lines of the speech, in which he remarks on his own deafness in one ear, suggest to the reader not only Caesar's age and physical limitations, but also that he has certain mental blind spots despite his political and intellectual astuteness.