For it is common with princes (saith Tacitus) to will contradictories: “Sunt plerumque regum voluntates vehementes, et inter se contrariæ;”168 for it is the solecism of power to think to command the end, and yet not to endure the mean.
Kings have to deal with their neighbors, their wives, their children, their prelates or clergy, their nobles, their second nobles or gentlemen, their merchants, their commons, and their men of war; and from all these arise dangers, if care and circumspection be not used.
First, for their neighbors, there can no general rule be given (the occasions are so variable), save one which ever holdeth; which is, that princes do keep due sentinel, that none of their neighbors do overgrow so (by increase of territory, by embracing of trade, by approaches, or the like), as they become more able to annoy them than they were; and this is generally the work of standing counsels to foresee and to hinder it. During that triumvirate of kings, King Henry the Eighth of England, Francis the First, King of France,169 and Charles the Fifth, Emperor, there was such a watch kept that none of the three could win a palm of ground, but the other two would straightways balance it, either by confederation, or, if need were, by a war; and would not, in any wise, take up peace at interest; and the like was done by that league (which Guicciardini170 saith was the security of Italy) made between Ferdinando, King of Naples, Lorenzius Medicis, and Ludovicus Sforza, potentates, the one of Florence, the other of Milan. Neither is the opinion of some of the schoolmen to be received, that a war cannot justly be made, but upon a precedent injury or provocation; for there is no question, but a just fear of an imminent danger, though there be no blow given, is a lawful cause of a war.