Final answer:
Cicero uses the appeal to ethos in order to elevate his argument and give it a distinct style.
Step-by-step explanation:
Cicero's purpose for using the appeal to ethos in the line 'Shame on the age and on its principles!' is to elevate his argument by giving it a distinct style. By expressing his shame and disapproval of the principles of the age, Cicero aims to persuade the senators by appealing to their sense of honor and pride. This rhetorical device helps Cicero's argument stand out and adds a sense of urgency and gravitas to his message.