Final answer:
Comets in the excerpt from Julius Caesar represent evil omens, historically associated with the death of important figures and catastrophic events.
Step-by-step explanation:
In the excerpt from Julius Caesar, act 2, scene 2, the symbol of comets represents evil omens. Calpurnia mentions that comets are not seen when beggars die, but the heavens blaze forth the death of princes, indicating that comets were believed to herald the death of significant figures or catastrophic events. This stems from historical legends and cultural beliefs that associated the appearance of comets with negative events such as the deaths of kings, losses in wars, or ends of dynasties.