Niccolò Machiavelli
Discourses on the First Decade of Titus Livius (Chap. 1.22)
What is to be noted in the combat of the three Roman Horatii and the three Alban Curiatii.

It was agreed between Tullus king of Rome, and Metius king of Alba, that the nation whose champions were victorious in combat should rule over the other. The three Alban Curiatii were slain; one of the Roman Horatii survived. Whereupon the Alban king with all his people became subject to the Romans. The surviving Horatius returning victorious to Rome, and meeting his sister, wife to one of the dead Curiatii, bewailing the death of her husband, slew her; and being tried for this crime, was, after much contention, liberated, rather on the entreaties of his father than for his own deserts.

Herein three points are to be noted. First, that we should never peril our whole fortunes on the success of only a part of our forces. Second, that in a well-governed State, merit should never be allowed to balance crime. And third, that those are never wise covenants which we cannot or should not expect to be observed. Now, for a State to be enslaved is so terrible a calamity that it ought never to have been supposed possible that either of these kings or nations would rest content under a slavery resulting from the defeat of three only of their number. And so it appeared to Metius; for although on the victory of the Roman champions, he at once confessed himself vanquished, and promised obedience; nevertheless, in the very first expedition which he and Tullus undertook jointly against the people of Veii, we find him seeking to circumvent the Roman, as though perceiving too late the rash part he had played.

This is enough to say of the third point which I noted as deserving attention. Of the other two I shall speak in the next two Chapters.