Destruction
When describing The Great Fire of Rome, Tacitus uses imagery to describe the destruction it caused. For example, he describes how the city was "burning," emphasizing the destructive nature of this disaster. He uses this as an example of Nero's incompetence as a leader.
Historical bias
When Tacitus is introducing the book, he talks about the historical bias that has clouded perception of the past. He states that Augustus in particular has been misrepresented, using imagery to reinforce this point. For example, he states that accounts were "falsified through terror" and that they were "written under the irritation of a recent hatred." He also describes these accounts as being marred by "bitterness or partiality."
The role of a historian
Tacitus writes about his role as a historian, and the duty he has to record the past truthfully. He uses imagery to describe his role, saying that it is his "duty" to "confront evil words and deeds with the fear of posterity’s denunciations." Overall, this use of imagery adds an emotional dimension to Tacitus' argument.