Quote from Cicero's On Ends:
"This being the theory I hold, why need I be afraid of not being able to reconcile it with the case of the Torquati my ancestors? Your references to them just now were historically correct, and also showed your kind and friendly feeling towards myself; but the same I am not to be bribed by your flattery of my family, and you will not find me a less resolute opponent. Tell me, pray, what explanation do you put upon their actions? Do you really believe that they charged an armed enemy, or treated their children, their own flesh and blood, so cruelly, without a thought for their own interest or advantage? Why, even wild animals do not act in that way; they do not run amok so blindly that we cannot discern any purpose in their movements and their onslaughts.
Can you then suppose that those heroic men performed their famous deeds without any motive at all? What their motive was, I will consider later on: for the present I will confidently assert, that if they had a motive for those undoubtedly glorious exploits, that motive was not a love of virtue in and for itself.—He wrested the necklet from his foe.—Yes, and saved himself from death. But he braved great danger.—Yes, before the eyes of an army.—What did he get by it?—Honor and esteem, the strongest guarantees of security in life.—He sentenced his own son to death.—If from no motive, I am sorry to be the descendant of anyone so savage and inhuman; but if his purpose was by inflicting pain upon himself to establish his authority as a commander, and to tighten the reins of discipline during a very serious war by holding over his army the fear of punishment, then his action aimed at ensuring the safety of his fellow citizens, upon which he knew his own depended.
And this is a principle of wide application. People of your school, and especially yourself, who are so diligent a student of history, have found a favorite field for the display of your eloquence in recalling the stories of brave and famous men of old, and in praising their actions, not on utilitarian grounds, but on account of the splendor of abstract moral worth. But all of this falls to the ground if the principle of selection that I have just mentioned be established,—the principle of forgoing pleasures for the purpose of getting greater pleasures, and enduring, pains for the sake of escaping greater pains.