“Wars,” says Cicero, “are to be undertaken for this end, that we may live in peace without being injured; but when we obtain the victory, we must preserve those enemies who behaved without cruelty or inhumanity during the war: for example, our forefathers received, even as members of their state, the Tuscans, the Æqui, the Volscians, the Sabines and the Hernici, but utterly destroyed Carthage and Numantia.... And, while we are bound to exercise consideration toward those whom we have conquered by force, so those should be received into our protection who throw themselves upon the honour of our general, and lay down their arms,” (_op. cit._, I. xi., Bohn’s Translation).... “In engaging in war we ought to make it appear that we have no other view but peace.” (_op. cit._, I. xxiii.) In fulfilling a treaty we must not sacrifice the spirit to the letter (_De Officiis_, I. x). “There are also rights of war, and the faith of an oath is often to be kept with an enemy.” (_op. cit._, III. xxix.) This is the first statement by a classical writer in which the idea of justice being due to an enemy appears. Cicero goes further. Particular states, he says, (_De Legibus_, I. i.) are only members of a whole governed by reason. In the Middle Ages the development of these ideas received little encouragement. All laws are silent in the time of war,[25] and this was a period of war, both bloody and constant. There was no time to think of the right or wrong of anything. Moreover, the Church emphasised the lack of rights in unbelievers, and gave her blessing on their annihilation.[26] The whole Christian world was filled with the idea of a spiritual universal monarchy. Not such as that in the minds of Greek and Jew and Roman who had been able to picture international peace only under the form of a great national and exclusive empire. In this great Christian state there were to be no distinctions between nations; its sphere was bounded by the universe. But, here, there was no room or recognition for independent national states with equal and personal rights. This recognition, opposed by the Roman Church, is the real basis of international law. The Reformation was the means by which the personality of the peoples, the unity and independence of the state were first openly admitted. On this foundation, mainly at first in Protestant countries, the new science developed rapidly. Like the civil state and the Christian religion, international law may be called a peace institution. [25] The saying is attributed to Pompey:—“Shall I, when I am preparing for war, think of the laws?” [26] This implied, however, the idea of a united Christendom as against the infidel, with which we may compare the idea of a united Hellas against Persia. In such things we have the germ not only of international law, but of the ideal of federation. _Grotius, Puffendorf and Vattel._