M. Tullius Cicero Pro L. Murena 65

[65] And even you yourself, (at least that is my opinion and expectation,) excited as you are at present by the impetuosity of your disposition and elated as you are both by the vigour of our natural character and by your confidence in your own ability, and inflamed as you are by your recent study of all these precepts, will find practice modify them and time and increasing years soften and humanise you. In truth, those tutors and teachers of virtue, whom you think so much of appear to me themselves to have carried their definitions of duties somewhat further than is agreeable to nature, and it would be better if, when we had in theory pushed our principles to extremities, yet in practice we stopped at what was expedient. “Forgive nothing.” Say rather, forgive some things, but not everything. “Do nothing for the sake of private influence.” Certainly resist private influence when virtue and good faith require you to do so. “Do not be moved by pity.” Certainly if it is to extinguish all impartiality; nevertheless, there is some credit due to humanity. “Abide by your own opinion.”