The Law of Nations or the Principles of Natural Law (1758)Emmerich de Vattel Of the Right to Security, and the Effects of the Sovereignty and Independence of Nations§ 49. Right to security.§ 50. It produces the right of resistance;§ 51. and that of obtaining reparation;§ 52. and the right of punishing.§ 53. Right of all nations against a mischievous people.§ 54. No nation has a right to interfere in the government of another state.§ 55. One sovereign cannot make himself the judge of the conduct of another.§ 56. How far lawful to interfere in a quarrel between a sovereign and his subjects.§ 57. Right of opposing the interference of foreign powers in the affairs of government.§ 58. The same rights with respect to religion.§ 59 No nation can be constrained with respect to religion.§ 60. Offices of humanity in these matters. Missionaries.§ 61. Circumspection to be used.§ 62. What a sovereign may do in favor of those who profess his religion in another state.
     1.    Garcillasso de la Vega.
     2.    When, however, we see a party inflamed with deadly hatred against the religion we profess, and a neighboring prince persecuting in consequence the professors of that religion, it is lawful for us to give assistance to the sufferers, — as it was well remarked by James I. of England to Bouillon the ambassador of Mary de Medici, queen-regent of France, — "When my neighbors are attacked in a quarrel in which I am interested, the law of nature requires that I should anticipate and prevent the evil which may thence result to myself." — Le Vassor, History of Louis XIII.
     3.    See above, § 46, and Bodinus's Republic, book i. c, ix, with his quotations, p.m. 139.