The Republican leaders do not talk to the public of these almost certain results of success in the present conflict. They talk but little, in the existing emergency, even of the original cause of quarrel. The most ordinary policy teaches them to inscribe on their banner that part only of their known principles in which their supporters are unanimous. The preservation of the Union is an object about which the North are agreed; and it has many adherents, as they believe, in the South generally. That nearly half the population of the Border Slave States are in favor of it is a patent fact, since they are now fighting in its defence. It is not probable that they would be willing to fight directly against slavery. The Republicans well know that if they can reëstablish the Union, they gain everything for which they originally contended; and it would be a plain breach of faith with the Southern friends of the Government, if, after rallying them round its standard for a purpose of which they approve, it were suddenly to alter its terms of communion without their consent. But the parties in a protracted civil war almost invariably end by taking more extreme, not to say higher grounds of principle, than they began with. Middle parties and friends of compromise are soon left behind; and if the writers who so severely criticize the present moderation of the Free-soilers are desirous to see the war become an abolition war, it is probable that if the war lasts long enough they will be gratified. Without the smallest pretension to see further into futurity than other people, I at least have foreseen and foretold from the first, that if the South were not promptly put down, the contest would become distinctly an antislavery one; nor do I believe that any person, accustomed to reflect on the course of human affairs in troubled times, can expect anything else. Those who have read, even cursorily, the most valuable testimony to which the English public have access, concerning the real state of affairs in America--the letters of the _Times'_ correspondent, Mr. Russell--must have observed how early and rapidly he arrived at the same conclusion, and with what increasing emphasis he now continually reiterates it. In one of his recent letters he names the end of next summer as the period by which, if the war has not sooner terminated, it will have assumed a complete anti-slavery character. So early a term exceeds, I confess, my most sanguine hopes; but if Mr. Russell be right, Heaven forbid that the war should cease sooner; for if it lasts till then, it is quite possible that it will regenerate the American people.