The main reason why Brutus believes that Caesar must die has to do with the people crowning Caesar as king; he believes that Caesar will have too much power, and may use this power in ways that might not best benefit Rome.
Answer:While Brutus did not give exact reasons for murdering Caesar, he and the 40 senators that killed the dictator did so collectively because they felt Caesar was a threat to their own positions in the Senate. Caesar not only appeared on the denarius coin but was named by some senators as dictator in perpetuity. The motive for the killing then was sparked by Caesar's supposed claims of kingship.
The topic sentence is usually the first (or sometimes the second) sentence of a paragraph. It summarizes the paragraph as well as identifies the main point.
