Final answer:
The question seeks an example of a historical allusion in Shakespeare's play Julius Caesar, which features many such references to Roman history and notable figures like Caesar, Brutus, and Antony. A specific quotation is not given, but the play contains multiple instances that could qualify.
Step-by-step explanation:
The question asks for an example of a quotation from Shakespeare's play Julius Caesar that contains a historical allusion. An allusion is an indirect reference to a person, event, place, or piece of literature. In the context of Julius Caesar, a historical allusion refers to a reference made about historical figures or events related to Roman history that would have been familiar to Shakespeare's audience. This play is rich in such allusions, as it deals directly with historical figures like Julius Caesar, Brutus, and Mark Antony, and events such as Caesar's assassination and the political turmoil that followed.
A well-known example of a historical allusion in Shakespeare's Julius Caesar could be found in Act 3, Scene 1, when Caesar is assassinated. The conspirators refer to historical figures and events such as when Cassius mentions, "How many ages hence shall this our lofty scene be acted over in states unborn and accents yet unknown!" This allusion to the lasting impact of Caesar's death hints at the historical significance of the event and its remembrance in future generations.
As the question does not provide specific lines from the play, we cannot accurately determine which quotation from Julius Caesar contains a historical allusion. However, examining the play will reveal numerous examples where characters refer to past Roman figures or events, each of which could serve as an historical allusion.