Institutio Oratoria

Consequently, while to devote one's life to the task of accusation, and to be tempted by the hope of reward to bring the guilty to trial is little better than making one's living by highway robbery, none the less to rid one's country of the pests that gnaw its vitals is conduct worthy of comparison with that of heroes, who champion their country's cause in the field of battle. For this reason men who were leaders of the state have not refused to undertake this portion of an orator's duty, and even young men of high rank have been regarded as giving their country a pledge of their devotion by accusing bad citizens, since it was thought that their hatred of evil and their readiness to incur enmity were proofs of their confidence in their own rectitude.