The necessary distinction between law and ethics was drawn by Puffendorf,[31] a successor of Grotius who gave an outwardly systematic form to the doctrine of the great jurist, without adding to it either strength or completeness. His views, when they were not based upon the system of Grotius, were strongly influenced by the speculation of Hobbes, his chronological predecessor, to whom we shall have later occasion to refer. In the works of Vattel,[32] who was, next to Rousseau, the most celebrated of Swiss publicists, we find the theory of the customs and practice in war widely developed, and the necessity for humanising its methods and limiting its destructive effects upon neutral countries strongly emphasised. Grotius and Puffendorf, while they recommend acts of mercy, hold that there is legally no right which requires that a conquered enemy shall be spared. This is a matter of humanity alone. It is to the praise of Vattel that he did much to popularise among the highest and most powerful classes of society, ideas of humanity in warfare, and of the rights and obligations of nations. He is, moreover, the first to make a clear separation between this science and the Law of Nature. What, he asks, is international law as distinguished from the Law of Nature? What are the powers of a state and the duties of nations to one another? What are the causes of quarrel among nations, and what the means by which they can be settled without any sacrifice of dignity? [31] Puffendorf’s best known work, _De Jure Naturæ et Gentium_, was published in 1672. [32] _Le Droit des Gens_ was published in 1758 and translated into English by Joseph Chitty in 1797, (2nd ed., 1834). They are, in the first place, a friendly conciliatory attitude; and secondly, such means of settlement as mediation, arbitration and Peace Congresses. These are the refuges of a peace-loving nation, in cases where vital interests are not at stake. “Nature gives us no right to use force, except where mild and conciliatory measures are useless.” (_Law of Nations_, II. Ch. xviii. § 331.) “Every power owes it in this matter to the happiness of human society to show itself ready for every means of reconciliation, in cases where the interests at stake are neither vital nor important.” (_ibid._ § 332.) At the same time, it is never advisable that a nation should forgive an insult which it has not the power to resent. _The Dream of a Perpetual Peace._