VII. In exacting punishment it is necessary to use the precaution of avoiding hostilities with a power of equal strength. For to avenge a wrong, or to assert a right by force of arms requires a superiority of strength. So that not only prudence, but a regard for their subjects will at all times deter rulers from involving their people in the calamities of war. A principle of justice too, the sole directress of human affairs, binding sovereigns and subjects to each other by their mutual interests, will teach this lesson of precaution. For reparation must be looked for at the hands of those, who bring on the calamities of wanton and unnecessary war. Livy calls that a just, which is a necessary war, and it is a pious cause, when no hope is left, but in recourse to arms. VIII. It is but now and then a cause of such imperious necessity occurs, as to demand the decision of the sword, and that is, when, as Florus says, the desertion of a right will be followed by calamities far more cruel, than the fiercest wars. Seneca says, "that it is right to meet danger, when equal harm would result from acquiescing in an injury," and in this, he is supported by Tacitus, who calls "war a happy exchange for a miserable and insecure peace," and the same animated writer in another place observes, that "an oppressed people may recover their liberty by daring enterprize, and, if defeated they cannot be reduced to greater subjection than before;" a sentiment, with which Livy accords, in naming "peace, when coupled with servitude, a far more grievous calamity, than all the horrors of war." But it is not so, as Cicero says, where defeat will be attended with proscription, and victory with bondage. IX. Another necessary precaution relates to the TIME, when it is proper to undertake a war, which depends upon a due calculation, whether there are resources and strength sufficient to support our just pretensions. This is conformable to what was said by Augustus, that no war should be undertaken, but where the hopes of advantage could be shewn to overbalance the apprehensions of ruin. Scipio Africanus, and Lucius Aemilius Paulus used to speak in terms not inapplicable to this subject, for they said "it was never right to try the event of battle, but under extreme necessity, or favourable circumstances." The above precautions are of great use, where we hope by the dread and fame of our preparations to accomplish our object with little or no danger. CHAPTER XXV. THE CAUSES OF UNDERTAKING WAR FOR OTHERS. Sovereigns may engage in war to support the rights of their subjects--Whether an innocent subject can be delivered up to an enemy to avoid danger--Wars justly undertaken in support of confederates upon equal, or unequal terms--For friends--For any men--Omission of this duty not blamable, from motives of self-preservation--Whether war may be justly undertaken in defence of another's subjects, explained by distinctions.