Montesquieu

“ Treaties of peace are so sacred among men, that they seem to be the voice of nature reclaiming her rights. They are quite legitimate, when the conditions are such that both nations can preserve themselves; without that, the nation which would perish, deprived of its natural defence by peace, may seek safety in war. ”

“ No greater insult can be offered a prince, than to renounce his alliance, and no greater honour can be conferred upon him, than to enter into one with him. Nothing on earth adds more to our honour, and is really more useful, than to see others always careful of our preservation. ”

“ MAGISTRATES ought to do justice between citizen and citizen; and each nation between itself and other nations. In this second administration of justice, no other maxims should be employed than in the first. ”

“ The reason of this is, that, since a declaration of war ought to be an act of justice, which always requires the punishment to be proportioned to the crime, it is necessary to make sure that he upon whom war is declared merits death: for to wage war on any one is to pronounce against him the death penalty.
In international law the severest act of justice is war, since it may have the effect of destroying society. ”

“ A third act of justice is to deprive a prince of the advantages which he may derive from us, always measuring the penalty by the offence.
The fourth act of justice, which ought to be the most frequent, is to renounce the alliance of a people which gives cause of complaint. ”

“ As they live together, their interests are so intermingled and so confused, and also so various that it is necessary for a third party to clear that which the covetousness of the other two endeavours to obscure. ”