Final answer:
The author is inferring that Cassius is referencing Shakespeare's time, and the historical context is the political upheaval when Shakespeare wrote Julius Caesar.
Step-by-step explanation:
The inference made by the author is that Cassius is referencing Shakespeare's own time, and the historical context on which the inference is based is the political upheaval during which Shakespeare wrote Julius Caesar. Shakespeare wrote the play during a time of great political upheaval, and the character Cassius's quote suggests that the events in the play would be relevant and acted out in future generations. This connects to the historical context of Shakespeare's time and the anticipation of the play being performed in states and languages yet unknown.