It was this state of things which made possible the curious interlude of the "Know-Nothing" movement, which cannot be ignored, though it is a kind of digression from the main line of historical development. The United States had originally been formed by the union of certain seceding British colonies, but already, as a sort of neutral ground in the New World, their territory had become increasingly the meeting-place of streams of emigration from various European countries. As was natural, a certain amount of mutual jealousy and antagonism was making itself apparent as between the old colonial population and the newer elements. The years following 1847 showed an intensification of the problem due to a particular cause. That year saw the Black Famine in Ireland and its aggravation by the insane pedantry and folly of the British Government. Innumerable Irish families, driven from the land of their birth, found a refuge within the borders of the Republic. They brought with them their native genius for politics, which for the first time found free outlet in a democracy. They were accustomed to act together and they were soon a formidable force. This force was regarded by many as a menace, and the sense of menace was greatly increased by the fact that these immigrants professed a religious faith which the Puritan tradition of the States in which they generally settled held in peculiar abhorrence. The "Know-Nothings" were a secret society and owed that name to the fact that members, when questioned, professed to know nothing of the ultimate objects of the organization to which they belonged. They proclaimed a general hostility to indiscriminate immigration, for which a fair enough case might be made, but they concentrated their hostility specially on the Irish Catholic element. I have never happened upon any explanation of the secrecy with which they deliberately surrounded their aims. It seems to me, however, that a possible explanation lies on the surface. If all they had wanted had been to restrict or regulate immigration, it was an object which could be avowed as openly as the advocacy of a tariff or of the restriction of Slavery in a territory. But if, as their practical operations and the general impression concerning their intentions seem to indicate, the real object of those who directed the movement was the exclusion from public trust of persons professing the Catholic religion, then, of course, it was an object which could not be avowed without bringing them into open conflict with the Constitution, which expressly forbade such differentiation on religious grounds.