On the nineteenth of August Horace Greeley wrote his famous anti- slavery letter to the President, entitled "The Prayer of Twenty Millions." It was one of the most powerful appeals ever made in behalf of justice and the rights of man. In his reply Mr. Lincoln said: "If I could save the Union without freeing any slave, I would do it; if I could save it by freeing all the slaves, I would do it; and if I could save it by freeing some and leaving others alone, I would do that." These words served as fresh fuel to the fires of popular discontent, and they were responded to by Mr. Greeley with admirable vigor and earnestness. The anti-slavery critics of the President insisted that in thus dealing with slavery as a matter of total indifference he likened himself to Douglas, who had declared that he didn't care whether slavery was voted up or voted down in the Territories. They argued that as slavery was the cause of the war and the obstacle to peace, it was the duty of the Government to lay hold of the conscience of the quarrel, and strike at slavery as the grand rebel. Not to do so, they contended, now that the opportunity was offered, was to make the contest a mere struggle for power, and thus to degrade it to the level of the wars of the Old World, which bring with them nothing for freedom or the race. They insisted that the failure of the Government to give freedom to our millions in bondage would be a crime only to be measured by that of putting them in chains if they were free. They reminded the President of his declaration that a house divided against itself can not stand, and that the Republic can not permanently exist half slave and half free; and they urged that this baptism of fire and blood would be impious if the cause which produced it should be spared to canker the heart of the nation anew, and repeat its diabolical deeds. A Union with slavery spared and reinstated would not be worth the cost of saving it. To argue that we were fighting for a political abstraction called the Union, and not for the destruction of slavery, was to affront common sense, since nothing but slavery had brought the Union into peril, and nothing could make sure the fruits of the war but the removal of its cause. It was to delude ourselves with mere phrases, and conduct the war on false pretenses. It was to rival the folly of the rebels, who always asservated that they were not fighting for slavery, but only for the right of local self government, when the whole world knew the contrary. These ideas, variously presented and illustrated, found manifold expression in innumerable Congressional speeches and in the newspapers of the Northern States, and a month later brought forth the President's proclamation of the twenty- second of September, giving the insurgents notice that on the first day of January following he would issue his proclamation of general emancipation, if they did not in the meantime lay down their arms.