An impressive providential combination of causes determined this great historic movement of population at this time. It was effected by attractions in front of the emigrant, reinforced by impulses from behind. The conclusion of the peace of 1815 was followed by the beginning of an era of great public works, one of the first of which was the digging of the Erie Canal. This sort of enterprise makes an immediate demand for large forces of unskilled laborers; and in both hemispheres it has been observed to occasion movements of population out of Catholic countries into Protestant countries. The westward current of the indigenous population created a vacuum in the seaboard States, and a demand for labor that was soon felt in the labor-markets of the Old World. A liberal homestead policy on the part of the national government, and naturalization laws that were more than liberal, agencies for the encouragement of settlers organized by individual States and by railroad corporations and other great landed proprietors, and the eager competition of steamship companies drumming for steerage passengers in all parts of Europe--all these cooeperated with the growing facility and cheapness of steam transportation to swell the current of migration. The discovery of gold in California quickened the flow of it. As if it had been the divine purpose not only to draw forth, but to drive forth, the populations of the Old World to make their homes in the New, there was added to all these causes conducive to migration the Irish famine of 1846-47, and the futile revolutions of 1848, with the tyrannical reactions which followed them. But the great stimulus to migration was the success and prosperity that attended it. It was "success that succeeded." The great emigration agent was the letter written to his old home by the new settler, in multitudes of cases inclosing funds to pay the passage of friends whom he had left behind him. The great immigration that began about 1845 is distinguished from some of the early colonizations in that it was in no sense a religious movement. Very grave religious results were to issue from it; but they were to be achieved through the unconscious cooeperation of a multitude of individuals each intent with singleness of vision on his own individual ends. It is by such unconscious cooeperation that the directing mind and the overruling hand of God in history are most signally illustrated.