In spite of these experiences the idea of diplomatic intervention for the promotion of religious toleration in foreign States, especially on behalf of non-Christians, has only prevailed within narrow limits. It has been largely circumvented by the fact that such interventions must, even with the best will in the world, be more or less conditioned by the _raison d'état_. Unless they are likely to promote policy, or at any rate to coincide with policy, the usual course when they are invoked is to take refuge in the so-called principle of non-intervention. It was, indeed, not until the seventeenth century that the question was seriously discussed at all by the jurists, although Cromwell had already laid down the splendid principle, in the case of the persecution of the Vaudois, that "to be indifferent to such things is a great sin, and a deeper sin still is it to be blind to them from policy or ambition." The first impulses of the international lawyers were much in the Cromwellian spirit. Bacon, Grotius, and Puffendorff all strongly maintained the legality not only of diplomatic but also of armed intervention to put down tyranny or misgovernment in a neighbouring State, and a century later they were followed by Vattel. Sweden acted upon the principle in her intervention on behalf of the Protestants of Poland in 1707, and, in 1792, it was given its widest scope, and was formally adopted, by the French Revolution in the famous decree of the Convention which promised "fraternity and succour to all peoples who wish to recover their liberty." The doctrine, however, lingered only anæmically through the early decades of the nineteenth century. In face of the growing delicacy of the international system, it was gradually abandoned for the conservative principle of non-intervention, based on the independence and equality of all States.[7] But even this principle has not always been observed in regard to small States, although, curiously enough, Russia invoked it against Great Britain for the protection of King "Bomba" of Sicily, in the case of the Neapolitan prison horrors.[8] Abstention from intervention in certain glaring cases of inhumanity by foreign Governments--such as the persecution of the Russian Jews--has been defended on the ground of absence of treaty rights, but, as a matter of fact, this argument, too, has not been consistently adhered to.[9] In all cases, whether of great or small States, treaty rights or no treaty rights, the real test has almost always been the frigid _raison d'état_. The United States has been less affected by this restriction than the European Powers, and on many occasions has shown a really noble example of the purest altruism in international politics.[10] II. INTERVENTIONS ON GROUNDS OF HUMANITY.