What role does symbolism play in Julius Caesar and where does it appear?How Is the plot altered by the presence of these symbols?

Antony offers the crown to Caesar. This is symbolic that
Caesar was heaping up more honors for himself. The conspirators believe he is becoming a
dictator. The crown symbolized Caesar's growing popularity among the people. Although
Caesar refused the crown, he was becoming ambitious in his thoughts and deeds. In Act
one, Scene 2, Casca seemed to think Caesar pushed the crown away each time with less
force as if to indicate that he were truly considering
it:

CASCA:

Yes, damn it, it was, and he pushed it
aside three times, Every time more gently than the last, and at each pushing aside, My
honest neighbors shouted.

This crown symbolizes power.
Power symbolizes control. The conspirators do fear that Caesar desires more and more
power and control.

Another area of symbolism is in Caesar's comment
about Cassius. He indicated that Cassius had a lean, hungry look about him. This worried
Caesar and is symbolic that Cassius desires power as well as Ceasar. Cassius makes
Caesar nervous:

CAESAR:

Let me have men about me that are
fat, Sleek-headed men, and such as sleep o' nights: Yond Cassius has a lean and hungry
look;(200) He thinks too much; such men are
dangerous.

Clearly, Caesar considers Cassius dangerous
because he has a lean, hungry look. This look is symbolic with a man who is hungry for
power. Rightly so, Cassius initiates the plot to kill Caesar.